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Lathe - Knurling

 
 

 

 
 
Knurling Do's and Don'ts? (Jul 20, 2001) Knurling question (Apr 18, 2004)
Knurling tool for lantern (Jan 24, 2003) Phase 2 knurling tool (Apr 18, 2004)
Knurling (Mar 31, 2003) Decent Knurling Tool (Dec 9, 2004)
Knurling (Apr 6, 2004)  
 
Knurling Do's and Don'ts?
Anyone have suggestions on how to go about knurling? I have a piece prepared that I'd like to apply about two inches (lengthwise) of medium knurling to. Is the knurling applied using manual control or under feed? Should several passes be taken to get to the correct depth of the knurl pattern? If several passes are taken, how does one assure that the tool stays in the pattern? Should low speed be used? Jim (1139)
I would practice on a test part first. If the pitch of the knurl isn't a multiple of the circumference of the part, it might not come out too good. Change part diameter if needed. I take one pass, slow rpm, lots of black cutting oil, under power feed. You can reverse the feed and go back if a little more is needed, but I wouldn't take it out of the pattern and restart. Push the knurling tool (or wrench it down, if you have the clamp type), and rotate the part back and forth by hand, as more pressure is applied, until you are a little shy of the depth you want. This seems to help get it started properly, especially if the pitch is off a bit. Don't go too deep, or it gets messy looking, nowhere for displaced metal to go. Leave a small flat on top. It takes a little practice, but you'll get a justified sense of accomplishment when it comes out crisp. (1140)
Looks like excellent advice. I'll give it a try on a test piece. As a rule of thumb, do you use a power feed in the middle of the range? Jim (1141)
OK, so I'll stick my foot in some good 'ol shop manure. An operation of this type really puts your creme-puff on PMS. Punishing MY SouthBend! I'd do this with some sort of 'clam-shell' type of rig. On hand-screw machines we use a tool attached to the top or side of the lathe. It can also be bought along with a quick-change tooling system. Hmmm...I'm not really doing this justice here, so let me start again. Knarling is in my humble opinion THE WORST THING YOU CAN DO WITH YOUR LATHE! Your taking a PRESSING tool and jamming it against those 'not so young' castings and bearings. In the words of an MSC instruction sheet, "In order to get a real good imprint you must (GULP!) jam the tool against the work". Call me a sissy if you want but I'd rather eat babbitt bearings before I'd do this to my lathe. Instead get this hear unit that works like a clamp and exerts it's own pressure while putt'in wrinkles on your work. When that lathe was young, you probably could do this on a lathe. But it really will put a strain on everything involved. If you must, buy an old junker with a worn-out everything and rig IT to do yer dirty-work! Ron (1142)
I'd agree completely with Ron, and I would not use either the single or dual knurl pivoting head types on my Heavy 10 for the reasons he stated unless the material was soft and an aggressive (deep) knurl wasn't necessary. Fortunately, there are two other types resembling Ron's clamshell approach that are fairly benign. The first is probably the best you can get, and that is a fork shaped arrangement which has two knurls opposed on the ends of the fork. This is the type of tool used for the cleanest knurls in a production environment, using a fine wire brush to keep the knurls clean and plenty of lubricant as the knurls are feeding. With the B S style, you can do both straight and diamond knurls with the same straight knurls - the guides rotate to whatever angle is needed. The other style is the scissors type that does about the same thing, but in my experience has rigidity problems with tougher materials unless you get a robust model. Your experience may differ, and that's fine...either type places only a reactive torque on the spindle and tailstock, which they were designed to absorb. Properly set up, they don't put any pressure on the bearings at all, which is ideal. The drawback? More time and "fiddle factor" to set up, and the B S style does require 2 or 3 tools to cover a complete range of diameters. The side feeders are pretty much set and go, at the expense of bearing wear and a level of breathtaking apprehension way above my tolerance level. The high-end Brown Sharp knurling tools come up on the bay place all the time - I think I paid all of $40 for mine, and it runs from .375" to about 1.375" with a convenient 1" shank that fits the Aloris boring tool holder perfectly. Do a Google search on rec.crafts.metalworking using 'Bastow' as the author and 'knurling question' as the subject, and you'll see a good description of its use, along with what a real machining master thought of them. They *do* work beautifully, even on stainless steel! Mike (1144)
Evening everyone, I'm joining this discussion a bit late because I've been gone for a few days. First of all, I would like to say that I am partial to any type of straddle knurl holder. This type greatly reduces the destructive force applied to the machine components. I used to have a #5 Gisholt turret lathe and one of the regular jobs I used it for was putting about 8" of 20 TPI diamond knurl on 1-1/4" 304 stainless tube which was fabbed into grab handles used on fire apparatus. This was an interesting learning experience. I used a straddle knurling holder which was shop made by someone. I bought it used for next to nothing and modified it to use standard knurls, shoulder bolts for pins, homemade bronze bushings so the whole thing was renewable. The first thing in using a tool like this is to set it so that you get a full enough knurl by cross feeding in to about .015" short of center. This ensures that the tool will not pass over center (you won't like it when that happens). Then the long. feed could be engaged using around .020 IPR. This would make a nice clean knurl in one pass. One problem I did find was not being able to change the blank diameter since the tubing was already finished. I got around this by grinding a small amount off the O.D. of the knurls to make them track properly. Worked every time. Tom (1160)
You can get them from Enco. Larry (1230)
Knurling tool for lantern
I need to find a knurling tool to use with a lantern style tool post on my 9A. I've heard the clamp type is really the way to go, but everything I've seen is set up for a quick-change tool post or four way tool post. I've looked in Enco, KBC, Mcmaster, etc. and the shanks all look too wide to fit in the lantern. Tom (8883)
That shouldn't be a problem - most used machinery dealers have scads of these and they are available from Victor in NYC  www.victornet.com  Frank (8885)
KBC list some. Import and USA and Armstrong. They list the Clamp type too. Shank is 1/2X5/8 or 5/8X3/4 ($114 or $155 for USA or $60-80 import). The regular type Cost $15 for the pivot head or $40-55 for the multi-type. I thought I saw them in MSC. KBC's number is 1-800-322-4292. Tom (8887)
I checked out www.victornet.com , but didn't see what I think will work. I guess I should have called it a scissors type. The ones I've seen all have a shank at least 1/2" in width, more than my lantern post can handle. Maybe I'm being overly paranoid about needing a scissors type? I've heard the other style puts too much pressure on the bed ways. Tom (8888)
Tom, I have an older MSC catalog. It list The clamp type or adjustable with a 3/8 shank. 1/8-1 capacity. It cost $123.20. Order # 08656027. Tom (8889)
Tom, Another solution would be the hand knurlers. They don't mount to the tool post. MSC list two : 08681330 for $116 or $221 with 6 knurl set and 08681371 for $251. It looks like a pipe cutter. Tom (8890)
Mill the shank to fit. Make a new lantern post large enough to fit an unmilled shank. Rick K. (8891)
Victor has a 3/8 width shank self-centering knurl (not a scissor) in their paper catalogue for $24 bucks or so (I am looking at a yr old version) I bought one and it works just fine with my lantern holder on my 10K. Call them up (1-800-723-5359) and tell them its on page 48 of their 2001/2 catalogue. they also show a scissor type, but it seems to me that the shank is horizontal - not vertical. Personally, unless you are going into production knurling, I don't see that the forces will damage your ways. Use lots of oil, a very slow spindle speed and feed the tool in slowly. It will take several lateral passes to get the depth you want. I knurl a lot of brass knobs and just take my time with it. Frank (8892)
Tom, For my 9" SB I purchased the Enco (imported) Scissor type knurling tool on sale for $30 or $40. I removed the 1/2" x 5/8" arm and the pivot bolt throwing both away. I made a 1 1/4" x 1 3/4" x 2 1/4" high alum. block, drilled a 5/16" clearance hole vertically (with the 2 1/4" dim.) for a mounting bolt threaded into a CRS 1/4" thick plate sized to fit the T-slot in the compound. I then drilled a 3/8" horizontal hole 1 1/ '32" up from the base (SB distance from top of compound to centerline, check your machine). Put in a longer 3/8" pivot bolt through the two scissor arms and thru the aluminum block and your in business. Works great and is much more rigid than the original arrangement. CRS in lieu of the aluminum mounting block may even be better, I used aluminum because it was available and quick and dirty. Makes for an inexpensive, very usable, rigid, knurling tool. Neil (8893)
Knurling
I have seen many comments both here and on other boards about the negative effects of using a non pinch type knurling tool. The consensus seems to be that the lateral force required is hard on the bearings of my 9". Unless I miss something would not using a steady rest with the knurling tool on the tailstock side of the steady rest relieve the lateral forces on the headstock by being taken up by the steady rest? Perhaps I over estimate the support available from the steady rest. Does anyone know the answer to the viability of this technique? Jim (10043)
Jim, The pinch type is a superior method of knurling. Much easier to control and independent of the lathe cross feed. My worry with the old style is use with regular chucks getting the jaws sprung plus the stock to be knurled does not get overstressed. My usual parts are short stubs, so a steady rest would be no help. Building a pinch (scissors) knurler is an interesting project to make one. There are several plans floating around. I have built my own. RichD (10044)
Knurling is not just hard on the spindle, its hard on the apron too. Think about how the force is applied to the work with a single sided knurling tool. these lathes are not that rigid. the only resistance to horizontal loads is the incline of the way. Forces against the incline have 2 components, 1 horiz, the other vert. I will try to describe but w/o pictures, it may be hard to follow. Horizontal force will make the apron climb up the way until the bottom plate catches which resolves the vertical force. then the two work together to resist the force of the knurling. Pick up the apron on the machine. How much play is in there? that's enough to drive you batty. for single sided knurls, draw a picture of the knurl wheels and your work. Draw a radial line at the point of contact of each wheel and the work. Center to center of the knurl wheel to center of your work piece. Now draw the 'components' of those radial lines: these can be described as sin and cos of the angle. The two vertical forces are equal and opposite and cancel. the horizontal force is the sum of the two horizontal component. Now apply that horizontal force to the v way. to get and equal horiz component of the reaction on the 70 degree v to cancel the force of knurling, you have a relatively HUGE vertical force. That will go unchecked until the apron bears on the bottom of the apron. Scissor knurls by design will resolve the forces internally. one up, one down, the only one left is the resistance to travel along the work which is trivial. If anyone wants, I will sketch and post. dennis (10048)
Didn't SB themselves offer a QC toolpost with its OWN built in knurl? This thread has worried me a bit, having an older lathe that already has some slackness through wear. Seems like the scissors knurl would be worth posting in the files. Len (10050)
Since we're on Knurling, I have another type of knurling question: so far I've only used the diamond pattern knurls with two rotating wheel cutters. I want to make some simple straight-across (parallel lines, parallel to the long axis of the work) and see that there are two types for sale. One is a single wheel, the other is a more conventional double wheel (same as used for the cross-hatch or diamond pattern) How can one get a neat, clean, simple knurl if there are two wheels? since there's no way to align or synchronize each wheel, won't it bugger the knurl? Has anyone any tips about the single-wheel knurl? I knurl brass only - should I worry about the lateral loads on the bearings as per the previous few postings? Frank (10051)
Not to argue about the knurling but south bend shows and lantern style post with a knurling bar. Now for one lantern tool posts stink. And when you're trying to push the tool as hard as can into the piece of steel it's no wonder it moves. knurling can be done in a south bend lathe with a standard knurl it's just not good for a machine that has seen some wear ( and when was the last time you fired up you brand spanking new lathe?) It was probably fine back in the day when some one else owned the machine and you just ran it but this is your machine and if you break it you have to fix it. Kerry (10054)
The best general purpose knurling tool I have ever used is a hand-held three knurl device. Essentially the thing is a pair of handles about a foot long pivoted at one end, like a nutcracker. One handle carries two matched knurls about 1" apart and the other a single knurl which lies midway between the opposing pair when the handles are parallel. The pivot point is a bar with a series of holes to adjust the spacing of the handles so that they are more or less parallel when the tool is squeezed onto the workpiece. A stop screw sets the full squeeze travel. Having set the pivot point position to suit the workpiece diameter the tool is simply squeezed onto the workpiece with the lathe running is a slowish back gear speed and held until the desired depth of knurl is obtained. For longer knurls a slight sideways pressure in the desired direction causes the tool to move up and down the workpiece. Plenty of lubrication and a bit of patience gives a good knurl remarkably rapidly. With good sharp knurls it works well on all normal materials although really tough steels can a bit too much for it. Surprisingly, considering the normal load applied to conventional knurls, you don't have to squeeze terribly hard. Firm handshake (not knuckle-crusher) is about right. Too hard is as bad as too light. Basically you have to get a feel for it. The main disadvantage is the difficulty in putting a knurl in a precisely defined place. Usually one can trim to size afterwards but if it really matters I have been known to do the knurl first and make the rest of the part around it. Besides putting virtually zero stress on the lathe this tool seems to be immune from the annoying double knurl effect obtained when conventional tools "mis-register". Scissor type twin knurl tools can be exasperatingly sensitive to set-up it this respect. ( I have read magazine articles going into great detail as to how to calculate the exact starting diameter to get perfect knurls. If followed the procedures are said to "usually give perfect results". Unfortunately the various sets of calculations give different starting points so I suspect there is an element of workshop joss involved.) Personally I suspect that many problems encountered by HSM types are due to old, blunt, knurls and attempts to force the pace. Clive (10059)
Accu-trak http://www.accu-trak.com has some pertinent information on that very good question about tracking of multiple knurls, Frank. In the General knurling section, it says, "Two methods of specifying the comparative tooth spacing are currently in use - CIRCULAR PITCH and DIAMETRAL PITCH. snip Unlike gearing, only four standard pitches are used (64, 96, 128, 160) for blank diameters from 3/32" to 1". Diametral Pitch dies are designed to permit accurate tracking on standard fractional sized blanks, making blank diameter selection easier." Having said that, they also add in the Knurling "Tips" section, "Since proper tracking is usually established after only one complete revolution of the part, the "secret" to success is to RAM THE DIE INTO THE BLANK!! By forming a deeper, wider impression on the first revolution, the die teeth are more likely to "step" back into the initial grooves the second time around." So...there is obviously a bit of slop associated with the forming process to allow the "stepping" to occur on each revolution. I have both forming and cutting knurl types for my HLV-H, but I have all but abandoned the B S forming knurl tool. It's useful for increasing the diameter of worn shafts and the like, but in work-hardening materials like stainless and brass the peaks can appear 'crumbly' and uneven under a microscope after finishing, depending on the material, tool angles, pressure, and forming depth. The cutting knurl tool doesn't take any more power than normal turning or facing, has a capacity for 1/4" to 6" stock, and does a much nicer job in SS, AL, and brass than my big 2" B S compression type, IMO. The cutting type of knurl is apparently a bit more sensitive to the diameters and TPI than the forming type in preventing 'doubling', but I haven't had a problem with my particular sample of jobs. Lots of good info there on the Accu-trak website, including answers to your other questions about straight and diagonal knurling, feeds and speeds, etc. On the question of bearing wear caused by asymmetrical knurling tools, there's no question that you put a pretty good radial pressure on the spindle with one of those. The large plain spindle bearings used in South Bend lathes, *if* they have proper lubrication, are not usually bothered by such pressure - but the smaller the lathe the more potential you have for breaking through the lubricating film that provides the actual bearing. Cutting knurls, and balanced forming tools like the scissors and honkin' big U-shape straddle tools, reduce this side pressure significantly. Mike (10076)
With respect there is no way you can effectively "ram the knurling die into the blank" using a 9 or 10 inch SouthBend. The crossfeed leadscrews are far too slender and will simply spring buckle slightly under the applied load. Ramming works fine on big machine with a hefty feedscrew but it does have to be a solid push. Springyness just makes the original problem worse as any variation in cutting force, due to material variations, out or roundness, chip build up etc, will cause the knurl bounce in and out of cut slightly! That said the lighter loads produced by the cutting knurls advocated by Mike help considerably. I feel that, on small lathes having conventional "push" cross feed screws, knurling (and parting off) tools give best results when used in a rear toolpost. This places a tension load on the feedscrew making everything far more stable. Clive (10090)
Clive and all, With due respect, ramming is exactly the technique I use to knurl successfully. However, I think something may have been lost in the translation. This is how it's done. Bring the knurls into contact with the work. No rotation needed. Move the carriage to the right putting the knurls in the clear. Advance the knurler for a cut. Now start the lathe and move the carriage back to engage the work. This is the "ramming" part. Beveled knurls are best for this. By having a heavy feed at first forces the knurls (2) to track together most times. If the first try was too light a cut and mistracking is seen, roll back off the work, advance the feed and try again. Advance the feed only off the work. Always allow extra material for the starting area to be trimmed off later. The revs should be under 100 RPM and the entire operation should be completed in as few a number of revolutions as possible. Special calculations and diameters are not ever required. The whole thing happens faster than you can read this for perfect knurl. Oil is not strictly necessary but do keep the knurls clean with a brass brush. My knurlers are shop made and only the pinch type. RichD (10091)
Clive's comments are good observations and worthy of discussion - the bare Accu-trak quote could be interpreted to mean ramming the knurling tool radially into the workpiece, and that's not what was meant, AFAIK. 'Ramming' is the effect when the knurling tool. already set for correct engagement, encounters the workpiece as the carriage feeds the tool towards the headstock. Based on a fair amount of knurling on small ( 11") lathes, I think what they were actually trying to get across is that there is no room for timidity. In setting up the operation, you have to move the knurl(s) up to the point of touching, then advance a combination of the forming dimension plus compensation for any spring in the system. The latter is sometimes the killer, because we often try to perform these operations on slender workpieces without proper backup like a steady or follower rest. Obviously the balanced tools like the scissors and U-frame knurling tools have a lot less spring to factor into the mix. There is certainly a degree of experimentation required for most materials, and some sort of scribbling of what you've tried with your lathe is a useful part of every enthusiast's bookshelf. With a reasonably stiff workpiece, when you start the spindle and turn on the carriage feed toward the headstock, the moment of contact as it moves to the left truly appears like "ramming the die into the blank." It's one of those things that seems to defy our natural persuasion toward gentle treatment - but like parting off, too little can be disastrous. It applies as much to a small lathe as much as a large one, at least in my limited experience. (The largest lathe I've ever used had a 14" capacity, so I can't speak for anything larger.) The "ramming" is definitely a good description with knurling in my Heavy 10, somewhat less so in the 11" HLV-H. I wholeheartedly agree with the rear toolpost idea for parting off, but I need to better understand the physics of the reaction forces on a free turning knurling tool that would make a rear mount preferable, since there is no "lifting moment" as there is on a rear cutoff or turning tool. I need to noodle that one for a bit. I'm already biased towards rear toolpost usage, but this particular application needs further thought and trial. Unlike some materials like concrete, steel has the same strength in tension as it does in compression, but there may be some other reaction forces at work here. Mike (10092)
I'm not going argue if it can or can't be done on a small lathe with bushings. I'll just state my technique which has worked perfect every time well almost but it's the most reliable that I've found. Bring the knurls into contact with the part angled slightly so the left side of the knurl wheel will act as a lead in. you must do the following very fast to get it right and you need some guts to do it. Turn the lathe on to a med speed about 200RPM depending on your part diameter. As soon as the lathe comes on dial in pressure on the crossfeed and rock the carriage back and forth about .100" to .200" each way, this helps seat the knurls. Once you have the knurl about one forth pointed up stop the machine inspect the knurl to be sure you are tracking properly if all is well set the feed to about .010 to .015 per rev use oil or kerosene for steel or alum respectively. and hit the feed. at the end of the knurl stop the lathe reverse the feed and start the lathe back up. Now I've heard everyone's technique of knurling but no one has said how to fix it if it goes wrong. using my technique above if you don't get it right the first time you most likely didn't push hard enough on the crossfeed. so pick a new spot and try it again and this time push the friggin thing. Kerry (10096)
Humblest apologies for forgetting that bevel edged cutting knurls can be fed along in a manner similar to a normal turning tool and for not realizing that this was what was meant by ramming. Obviously the loads imposed are much lower and, more important, of the form a lathe is best designed to withstand. Handwaving analysis suggests a fairly significant longitudinal component (i.e. along the bed) to the cutting forces which must help. I was thinking in terms of forming knurls which need far more push into the workpiece. On a big lathe straight in radial feed is perfectly practical but a confident approach is essential for a clean start. In the words of my mentor "Ram 'er in boy!". Hence the confusion. Attempting to use forming knurls in this manner on a 9" SouthBend is not, in my experience, a rewarding experience. However I have successfully used direct radial feed with square edge forming knurls in a pivoting head type twin knurl holder mounted in a rear toolpost. I put the difference down to the better behavior of the cross feed screw in carrying a load under tension than under compression. It is well known that slender objects are much better at carrying loads in tension than compression. As the feed screw cross-section is effectively not much more than that of a 3/8" rod it hardly seems likely that it will take the forces of direct radial knurling without trying to buckle a bit. The Heavy 10 with taper turning attachment has a telescopic cross feed screw pulling from the rear so it normally operating in tension. Performance with parting and knurling tools in the normal toolpost is vastly better than the other 9" and 10" models. Some of this must be due to the heftier headstock spindle and bearings but I think the tension mode screw helps a lot. The parting off performance of my Heavy 10 is on par with a friends big 16" Harrison which has a much heavier headstock and a conventional 7/8" crossfeed screw. Clive (10097)
Knurling
Anyone have some good tips on knurling? What feed rates should be used? How are the diamond patterns rated? Bob (18240)
Run your lathe as slow as it will go. Use plenty of oil, I use pipe threading oil, and go back and forth advancing the tool in in very small amounts. Keep going over the same spot until you get the depth you want. You need different wheels for different size diamond patterns. Sorry but I don't know how they're rated. Joe (18244)
Most important of all the diameter of the piece being knurled must be a multiple of the tooth pitch of the knurl. This is necessary because knurling is a successive process of upsetting the surface were each revolution upsets a very small amount and you must increase the feed of the knurl as it makes its impression overtop of the previous revolution. Search the web for Knurling and you will find many explanations and procedures. Ted (18246)
Bob In the shop we recently I bought a clamp type knurling tool that fits in the Aloris type holders and you tighten onto the part instead of pushing against the part. You can check these out in any of the MSC tool catalogs or others. The only thing I can say is they are WONDERFUL. I would have bought one years ago if I only knew how nice and easy they operate. Watch the size range some are limited we found one that went from near nothing to two inches and are very happy with it. Some we checked out went like half inch to inch and a half . We have med and coarse wheels and find that is all we need, probably could get by with just med. Grumpy (18262)
Bob Starting the pattern is the toughest part. As someone else pointed out, go very slow and use lubrication. Make sure the tool is even with the center of the work piece. I usually start the pattern turning the spindle by hand. Start the knurl close to edge if possible or if it is not near an edge, tilt the tool slightly so that only one side digs in. This puts more pressure on a small area of the metal and will help to get a good pattern going. Once the pattern has started you can straighten the tool out, carefully re- engage the wheels and it will follow the pattern you established. I have knurled many different diameters using the same size tool so roller diameter is not a big issue. Ron  (18265)
As ever its a great help to know your tool. Inappropriate tooling is a prime cause of knurling troubles experienced by HSM types. There are two types of knurls:- Those that primarily Cut the the knurl and those that primarily Form the knurl by raising and depressing metal in appropriate parts. I've never used Cutting knurls as these are not easily available in UK. They are said to put much less stress on the lathe but I believe that they need to be fed in from the side like a normal cutting tool. Diameter of starting material is important with these knurls as the raising and depressing of material is much less. Forming knurls are (theoretically) fed straight in and put a lot of stress on the lathe. Conventional holders have a bar carrying a pair of knurls held in a floating pivot assembly so that they find the work centre line automatically. On a lightweight lathe its best to use them in a rear tool-post. On anything less than a Heavy Ten trying to use them in the normal tool post tends to be very frustrating as the lathe really isn't strong enough to generate the high and consistent pressure needed on the work-piece. Standard UK model engineer practice is to use forming knurls in a pinch holder with the knurls held diametrically opposite one another in a pair of pivoted arms with a pinch screw between them to apply the cutting load. Much kinder on the lathe. Obviously you slowly tighten the screw to deepen the knurl as the process proceeds. Can be tricky to start with both knurls working together. Get it wrong and you get the weird double knurl effect. It is important to have the knurls accurately set on the lathe centre line. I have a very effective hand held knurling tool which carries three matching knurls in two against one formation on a pair of pivoted arms. The arms are pivoted in front of the knurls and squeezed together like a pair of nutcrackers. The pivoting arrangements allow you to adjust the arm spacing to suit the work-piece diameter. These work very well on all materials once the holding and traversing knack has been acquired. I tend to run at either bottom direct drive or top back gear speeds on the Heavy 10, mostly my knurled pieces are between 0.5 and 1.5 inch diameter. The three knurl tool seems impervious to multiple starts so, if I were to make or specify a knurling tool for a small lathe, I'd use this format on a pinch type holder. It is often said that "the diameter of the piece being knurled must be a multiple of the tooth pitch of the knurl". For forming knurls this is something of an "old fitters tale". For any relationship between knurl pitch and work diameter that produces a job of aesthetically acceptable appearance variations in the starting work-piece diameter merely alter the height and depth of the knurl relative to the starting body diameter. it also alters the amount of material actually cut out by the knurls. Many years ago I had this demonstrated to me on a heavy duty lathe. I would not however care to apply the feed loads used on any lathe of mine! With a small lathe its best to minimize the loads applied by the knurling process and starting near the correct diameter will be a great help. Do remember that the knurl will settle into cutting the pattern which needs least effort. Starting a fraction under theoretical diameter might be better as, with two knurls, if its exactly on diameter a double knurl pattern is just as "easy" as the single pattern. Obviously the three knurl tool suffers much less than a two knurl one from this sort of problem. Clive (18268)
I would agree with all that has been said. On a small lathe the only knurl to consider is the "pinch" type. I have received consistently better results. (18269)
While we're on knurling, I cannot figure out how to make a single (not diamond, but straight across) knurl. I bought a single-wheel knurl with straight teeth on the wheel, but this is crap. I work mainly in brass and aluminum and with little parts, so I don't have the feeling that I'm overstressing the cross-feed on my 10k, but will, some day try the pinch-type knurlers. But any advice on making straight knurls much appreciated Frank (18271)
Knurling question
What is the diameter tolerance on knurling? Lets say you have a .955 dia bar which is 3" circumference (to keep the math easy) and a 25 lpi diamond knurl (.04") This should generate 75 lines per circumference. The diameter should be a multiple of pitch/pi (.04/3.14...)or multiples of .0127" to get a clean knurl. How much can this diameter be off and still get a clean knurl? For a 14 lpi knurl the diameter should be in multiples of .0227" How much can this be off to get a clean knurl? Is the diameter tolerance for a straight knurl more or less critical? JP (18483)
If you have Machinery's Handbook it contains tolerances of diameters for knurling. If you don't then for 75 lpi the table shows a tolerance of +/- 0.001 to 0.0015 for the least critical class of knurl (class I and II). For high class (Class III) tolerance is + 0.000, - 0.0015. Ted (18484)
Phase 2 knurling tool
What is the size is of the knurls on their AXA equivalent tool holder, I come up with 1.6mm Is this correct, I can't find any catalog info other than med knurls. (18495)
That's only 1/16". Do you mean 16 mm? (5/8" diameter) Usually the problem is matching the bore and width size. BTW, all that fussing with diameters is hogwash. Knurling any diameter with any knurl set is a simple technique. Use bevel edged knurls set dead square with the stock. Very slow speed and use as few revolutions as possible. Start from the edge after touching the knurls on the stock. Close the knurler slightly and run onto the stock slightly. Check for tracking. If not close more and try again. A heavy feed from the start will almost guarantee tracking. Slowly run across the stock and run back off. Close the knurler only off the stock. Do again if needed, but do so in as few revolutions as possible. Don't over do it. RichD (18497)
I went to the Phase II website at http://www.phase2plus.com  and then to the page on the knurling tool. It says the size is 3/4" X 3/8" X 1/4". Dave (18499)
I was referring to the cutting pitch. I ran it against a piece of well oiled stock just for the hell of it. The stock was approx .935 and it produced 46 clean diamonds around the stock. The pattern was not full depth, it was only .01 to see how the tool worked, I expected an odd cut, not a clean one. I am not quite sure of the starting diameter because I used an old caliper that was handy, not the known good one. I figured it was probably 14 lpi which is common, it calculates to be 15.66 or so. The closest standard knurl I found that is close is 1.6mm and with that the stock should have been .922". I went to look up the pitch of the tool and hit a dead end. So I ask, what is the pitch supposed to be? When I went looking for metric knurls I found 15 degree as well as 30 degree and straight but no female knurls, metric or imperial on a quick search. JP (18502)
I found info on knurling at www.doriantool.com/Knurling/Knurling_Catalog.pdf  There is info in here on straight knurls, someone asked about that a while ago. What I was looking for is on page 14 optimum blank diameter and correction factor. Technical info is the first third of the catalog, tooling made in the USA. I measured the Phase 2 knurling tool and found 37 teeth on 3/4" diameter which comes out to 1.6mm transverse pitch. I called Phase 2 and asked what the pitch is and the person I spoke to didn't know and couldn't find the info, what an outfit! Tooling made offshore. JP (18525)
Decent Knurling Tool
JP I find the hand held, hand squeezed, three wheel "nut-cracker" type tool very good for virtually all my knurling. I've got tool post mount types somewhere but have not used them for so long that the little man who lives under the bench probably had them away sometime in the last decade. Unfortunately these seem very rare but can be made quite easily. I've got some DIY drawings for one which is a dead ringer for mine somewhere and could easily e-copy them to you if you are interested. Clive (22722)
I've sent details and pictures of this 3 wheel hand held tool off list to everyone interested. If I've missed anyone out E-mail me direct and I'll rectify the omission. I think putting details in the files should be done by some-one who actually builds the tool. I'm not convinced that an almost direct copy of the commercial one is the way to go for HSM types. Some things that are easy in a factory are hard for us and viky versa. To the best of my knowledge this tool went off the market in the mid 1970's so some small changes, e.g. to knurl sizes, to reflect what is currently available inexpensively may be sensible. I've only ever seen two, one at work and one in the "bin box" at the tool supplier I bought mine from. It cost me "50 pence for the knurls mate 'cos its obviously a rubbish tool". Despite knowing better I kept big mouth shut and paid with a smile. Good day that as I got a South Bend 9" Model A, literally fallen off the back of a lorry resulting in damaged handles, for 50 and a discount on the big pillar drill I went to buy. Clive (22758)
This thread has sparked off a bit more interest than I expected even though knurling is right up with parting off at the top of the least favorite job list. I think everyone wanting them now has copies of the drawings and pictures. If not please e-mail me off list. One thing I have found is that its much easier to keep track of this sort of distribution thing off-list rather than running through the digest. Putting it in the files seems a popular idea but we really should re-draw, verify component availability and modernize (if necessary) first. Seems sensible to aim for middle of next year to put a SBLG version up. I'm happy to act as contact guy for mods, suggestions and experiences so if anyone who builds it, uses it or has comments on the design "from making something with a similar bit in it" would care to e-mail me we will sort out a proper job that is also easy to make. Clive (22778)
 
     
 

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