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Lathe - Gear Cutting/Millerette

 
 

 

 
 
From the mill out pops a 48 tooth gear. (Apr 21, 2003) Millerette gear cutting attachment (May 5, 2004)
Gear Hobbing on a Lathe (Sep 8, 2003) Gear hobbing (Jun 2, 2004)
Old Southbend Gear cutting attachment (Feb 7, 2004) Gear Cutting (Dec 5, 2004)
Garrett Millerette (Feb 13, 2004) Gear cutting with millerette (Jan 23, 2005)
 
From the mill out pops a 48 tooth gear.
After the good luck I had with the AL test gear I went for it in steel. Made a 48 tooth change gear tonight a pic is at. http://tejasdragon.com/Today.html  The Wood Dragon (10354)
Looks great! did you grind the profile cutters yourself or buy? (would like to know where to buy or to find the profile) (10364)
Check here http://groups.yahoo.com/group/mwmills2/files/Duplex/  JWE (10365)
That's where I got the specs for it. I wrote a little vb program to figure the form tool sizes by what I need for DP, get outside diameter, tooth total depth angles and writes a gcode file to run the rotary table. I use the form tool pin info to draw the shape of the cutter # need in AutoCAD and print it out. When I get the material I'm going to make real form tools and make cutters instead of using the flycutter. The Wood Dragon (10376)
Have you checked out http://www.metalwebnews.com/howto/gear/gear1.html? Looks like a nifty way to fab cutters. Jeff (10410)
Yes, That's what I'll be doing as soon as I order some drill rod to make the cutters out of. The Wood Dragon (10414)
Gear Hobbing on a Lathe
Have any of you done Gear hobbing on a lathe or know of an accessory to do this type of operation. John (13832)
John http://groups.yahoo.com/group/mwmills2/files/Duplex/  In fact this whole group is dedicated to indexing/dividing and gear cutting. JWE (13833)
I've done gear hobbing on a lathe and it is really easy using a tap you hold the tap in the headstock and the gear is held on a shaft in the compound the gear must be the exact diameter that is needed and must be exactly on center with the tap you bring the gear forward into the tap with the cross feed and as it touches the tap it will start to spin (you can help it to start to spin with your hand) keep feeding into the tap a few thou at a time until the teeth are finished. fred (13836)
John, I made a threading indicator drive gear this way with a reasonable degree of success and have made other gears since. Make the hob Acme form of the pitch you want. Gash the teeth at an angle across the hob so they're not all starting to cut together. The outside diameter of the gear blank should be the pitch diameter of a gear with two more teeth than the number you want. Let the blank rotate freely on a spigot and advance the cut a few thou. at a time. This will generate a true involute profile. If you can arrange to positively drive the blank at the correct speed you're home free; the profile will be much cleaner. Have a go anyway! Rob (13839)
That technique would produce a gear designed to mesh with a worm. Does anyone know how they hob straight involute gears to be used in a gear train? By that I do _not_ mean the method where teeth are cut one at a time with a profile cutter. Dumitru (13853)
I've seen these gears cut, the cutter looks like a worm gear with teeth. The gears being cut were blanks stacked on a shaft. Everything was turning in time and the blanks started advancing toward the worm gear cutter. You could see the teeth being formed as it went through. I think the gear had to be at an angle to the cutter to make the teeth come out straight, it wasn't evident but that's the only way I can figure to compensate for the angle of the cutter. J.B. (13855)
I have come across a site on the Groups.yahoo sites which is dedicated Metal working gear cutting and indexing-MWMILL2 it has various accessories for gear cutting worth a look and I have come across an article on hobbing in the lathe which explains all that is required, I will find the information and take some notes for the site. John (13856)
I've seen that but didn't find the article explained things simply enough for someone not at all knowledgeable about gear cutting. For a straight flanked hob to cut an involute shape, it seems it would have to be moved in 2 directions at one, cutting both along the circumference of the gear blank and across it. John (13857)
Has anybody ever seen the tape by Jose F Rodriguez called cutting gears the easy way. I think it is a excellent start for anyone wanting to make gears . It covers a multitude of ways to cut gears and how to make your own gear hobb. Vinnie (13888)
Old Southbend Gear cutting attachment
Does any of the group members have a Southbend gear cutting attachment. I would like to know how it is constructed, as I would think they are no longer produced, and would like to make one for my self. John (17078)
This thing is from WW2 era. I saw it in the Le Blond version of H.T.R.A.L. Looks expensive. The text says you can make spur, angular and beveled gears with it. RC (17111)
I've seen the Garrett Millerette referred to in the South Bend literature too. Can't remember which catalog, but was probably around 1930 because I don't have much after that. (17205)
John, Got one of these. What questions do you have? I'll try answer them or take some pictures. Gary (17666)
Gary, can you post a picture of it? Sounds like a very cool accessory. I didn't know one was made. Eric (17673)
John Please take pics and post to the files area I am sure there are a lot of us my self included that would be interested in seeing it. I have thought about trying some gear cutting as I am missing some gears on my sbl. Jack (17687)
Here are some pictures at http://tinyurl.com/2vmsn  Will try take some more pictures of the vertical column next week and see about posting some of these in the photo section. The spindle that holds the gears is a Brown Sharp taper, no draw bolt is shown in the pictures. The change gears are: 16, 18 thru 31, 35, 37, 41, 43, 47, 49 and 60 teeth. gary S (17726)
That is similar to the ones made by Boxford and Myford in the UK for doing splines, keyways and gears. I do not have a picture of those units but I do of the Westbury one that you can machine yourself from castings sold by Working precision models in the UK. I have the complete construction article and drawings for this stored in the LatheMilling folder at mlathemods04. See attached picture for the simple version, the complex version uses worm gear dividing and swivels some what like the one your pictures show. JWE (17727)
Garrett Millerette
I found it in my catalogs. It is in 1934, but not 1929. In 1934, it was sold as "Gear Cutting Attachment for South Bend Lathes." It is shown as an attachment mounted on the compound rest. The text is ... " The Garrett Millerett Attachment for the lathe is equipped with a milling machine dividing head which enables it to be used for cutting gears of all kinds - spur, bevel, and angle. It will do graduating and milling, external key seating of all kinds, cutting at angle, splining, slotting and for milling small light work. Attachment is mounted on cross slide of lathe. Holds work in any position. Work can be spaced by turning it through any desired part of a revolution with the dividing head changeable gears. The index plate shows the proper gears to use for division from 2 to 360 and the number of turns required of the index lever. Equipment includes: 2 wrenches, 1 cutter arbor, 1 work arbor with draw bolt, 1 straight clamp, 1 dog center, 1 outboard support and 1 set of 24 change gears." It sold for $160 to $195 in 1934. You could buy a 9" Junior, equipped, for $188 that year. Jeff (17253)
Can you put a picture of the page in the photo section so everyone can see it? JP (17258)
There was a similar attachment described in Model Engineer in the mid 60s by Edgar T. Westbury. I have scans of the article stored at: http://groups.yahoo.com/group/mlathemods04/  in the lathe milling folder. The castings to build this from are still available from a supplier in the UK: http://www.wokingprecisionmodels.co.uk/ From my reading Wesbury designed this unit as a substitute for the very expensive Myford unit and to take care of the complaints users had expressed over most of the other after market units that were available then. It is a little large as drawn for a 7" lathe like the Myford or even a 9" like the South Bend but as soon as I can afford them I am going to order the castings to build one for myself. JWE (17264)
I think it pictured on pg 97 of HTRAL in the section on gear cutting on a lathe. JP (17270)
Thanks! Now it's obvious! Darrell (17279)
Yes! That is it. I thought I saw it somewhere else. HTRAL 1966, page 97 HTRAL 1941, page 97 HTRAL 1932, page 107 I couldn't find it in 1928 or earlier. Jeff (17295)
Millerette gear cutting attachment
 I am seeking info/manual on the rare Millerette gear cutting attachment for lathes. (18867)
There are pictures of it in the LeBlond lathe manuals. The title is "Running A Regal" and Lindsay has a reprint. RC (18896)
Gear hobbing
I'm wanting to hob some worm gears and was wondering if I could use a standard ACME tap as my cutter? JJ (19419)
I have set up a tap between centers and used it as a milling cutter to cut gears. However, I was never able to get it to cut and (drive) the gear. If you just want to hob the gear and have a way to index your gear blank it will work fine. Gary (19420)
Yes, JJ you can. Go to Chris Heapys (Model Engineer) site there is a lot of info on hobbing with a tap. Rick (19422)
Gear Cutting
I would assume one can buy the cutter to do this, but isn't the gap between teeth different on smaller gears than larger ones? But if this were true I guess large gears would not mesh with smaller ones? What is correct? I know one could grind a cutter out of a HSS toolbit. Doesn't seem real easy as this has to be a pretty perfect fit. I'm sure it can be done with enough patience and experience. The only gear cutting in my future might be to make a thread dial for my 9" SB. I have a mill/drill, but no rotary table or indexer for it. Making a gear on the lathe seems easier, just a small jig, and of course cheaper than buying those items for my mill/drill. Any ideas? Is this a project for the relative beginner? Alex (22574)
I have a Home Shop Machinist that shows how to make a thread dial from scratch for a 9" SB. Email me. Bob (22575)
The teeth are the same size, the involute profile is different for each gear. That is the curve on the sides of the tooth. On a rack they are straight and on a 5 tooth gear they are shaped somewhat like a candle flame. There are 8 or 9 gear cutters per gear pitch which cover most homemade gears. If you are making one gear then you just get the appropriate cutter. Look at McMaster's or MSC for info on 'involute gear cutters'. JP (22576)
As long as the DP is the same, any gear size will mesh with another. RichD (22578)
Thanks for the help. I'll look in my copy of the McMaster catalog for the gear cutters. Alex (22586)
Gear cutting with millerette
I have a problem that maybe someone can help with. I have the S.B. gear cutting attachment and a friend asked if I could make a couple of gears for him. I thought I would give it a try. He needs a 20 tooth and a 110 tooth set. After making a few parts to mount the attachment and a arbor for the cutter, I set up and made the 20 tooth gear. I think it came out pretty good. Now the problem. The attachment has a chart that shows divisions from 2 thru 50, and 360. It gives the change gear combination for each division, one gear on the lever and one gear on the worm shaft. I have been trying to figure out how to get the gear combo for 110 teeth. I assume you have to figure the worm ratio, the divisions, and ???? All the books I have that deal with indexing are the plate type head. I'm sure there's a connection but I'm not seeing it. The worm gear has 90 teeth so I guess that makes it 90:1 ratio. Chris (24210)
Unfortunately I'm not familiar with the "Millerette" so I have to speculate. If this is a 1:90 worm reduction, and if you select divisions from a change gear mounted on the worm shaft, and if you have a 44 tooth gear, install gear and index 36 teeth. If a 55 tooth gear index 45 teeth. If you cannot index directly to the gear on the worm shaft, mesh any gear with the 44 or 55, then index the appropriate number of teeth on the second gear (36 or 45 respectively). Please tell me if this solves your problem. Whether this solves the problem or not, please give me more info on the "Millerette". I'm interested in all dividing mechanisms and the information may enable me to be more helpful. Anthony (24220)
http://metalworking.com/DropBox/_2004_retired_files/Millerette%201.jpg  (24221)
Chris I'm not sure how you have it set up (use simple indexing). But I'm assuming by lever, you mean the forward reverse lever. I'm also assuming that you are using a gear hob. With my 9" the lever stud gear turns at the same speed as the spindle, I think this is normal. So in your case to cut a 110 tooth gear you want the worm to turn 90 times (1 full revolution) while the spindle turns 110 times (to cut 110 teeth). Any gear ratio that will give you a speed reduction of 90:110 will work. I'd suggest checking my math with a known combination just to make sure it is correct. For your 20 tooth gear. It would be 90 turns of the worm shaft to 20 of the spindle so you would need to increase your speed by 90:20. Check to see if the combination in the instructions gives that ratio. John (24225)
Putting your 60 tooth gear on the worm shaft and your 49 tooth gear on the index lever with one turn of the index lever will turn the gear blank 3.2667 degrees. A 110 tooth gear has 3.2727 degrees per tooth. This may be close enough. (24226)
Rick posted a link to the pictures of the Millerette. Looking straight at the front I see a cross spindle on which the work is mounted and it has a 90 tooth worm wheel on its right end. Running vertically on the right side is a worm shaft meshing with the worm wheel, I presume this worm is a single start therefore producing a 1:90 reduction. At the top of the worm shaft a gear is mounted. To the left of the worm shaft is a stud to mount a gear to mesh with the one on the worm shaft, this stud having a crank to rotate the gear mounted on it and therefore to drive the gear on the worm shaft. I presume additional studs could be mounted for setting up a compound train but for this discussion that's not German. So, presuming the above description to be valid, and presuming you have the following: Mount a 44 tooth gear on the worm shaft. Mount a 36 tooth gear on the crank stud. Mark on tooth on the 36 so that it can always be set at the same reference spot. Set the 36 on the reference spot, lock the spindle, and cut first space. Unlock spindle, rotate crank one revolution to bring 36 to reference spot, lock the spindle, and cut second space. Repeat instructions for second space until you've come full revolution of the work piece. You should now have 110 spaces which was the original problem. The 36 tooth gear isn't necessary, it could be any count, it's just that 36 simplifies the counting. If any of these gears are not available to you, tell me what you have and I'll try to provide an alternative solution. Does this solve the problem? Anthony (24227)
Alternatively, make a 44 tooth gear per the index chart on the millerette and then mount the 44 tooth gear on the worm shaft and the 18 tooth gear on the index lever. Two turns of the index lever will turn the gear blank 3.27272727 degrees. This gear combination is almost perfect. (24228)
In my previous post, I forgot that you should have a 22 tooth gear in millerette gear set. Then, if you have both the 22 tooth and 18 tooth gears, put the 22 tooth gear on the worm shaft and the 18 tooth gear on the index lever, one turn of the index lever will turn the gear blank 3.272727 degrees. This combination will give you your 110 divisions per circle and you won't have to make any gears if you have the complete millerette gear set. (24231)
 
     
 

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