| MT2 taper reaming (May
27, 2003) |
Taper pin reamers (Oct
21, 2004) |
| Reamer question (Sep 4,
2003) |
Reamers (Jan 15, 2005) |
| |
| MT2 taper reaming |
| I tried reaming my
tailstock bore over the weekend with an MT#2 reamer, but couldn't
seam to get it to "bite". I first tried chucking the reamer in the
3-jaw, but had trouble keeping it from slipping. I switched to
turning the reamer by hand (with a wrench) and using the closed jaws
of the chuck to back-up the reamer axially. Nothing seamed to have
been happening, other than my arms getting tired and the tailstock
getting a bit warm. Am I doing something wrong? Tom (11493) |
| Look for: reamer teeth dull, even a
little bit would do it. Too much gunk or a glaze buildup in the
tailstock, chips here can ride on the reamer teeth and prevent them
from coming into contact with the bore. something in the tailstock
bore preventing the reamer teeth from entering far enough to contact
the bore - make sure there is NOTHING in there - slide the reamer in
by hand and see if the teeth all engage the bore try a little
kerosene, cutting fluid, WD40 or LPS, see if the teeth get any
better grip. You should at least get some scoring and some chips,
even with a moderately dull reamer. I would try it dead dry first
with moderate to light pressure until I could see what I got for
engagement , then try with fluid to take the working cuts. Are you
sure your tailstock bore isn't hardened? (11495) |
| When I reamed my
drill press, I found that the taper in that did not just end, but
had a shoulder that reduced the dia. that prevented the reamer from
entering all the way. Check to see what part of the reamer is
making contact then look for how to clear that. I hope it is not
something simple like spinning it the wrong way or that you had the
tailstock so far in the screw prevented the reamer from engaging
fully. Oh, and by the way, do not expect every blade to cut, it is
quite possible that only one blade will be doing all the cutting.
Dave (11497) |
| Are you certain that the reamer is
being turned the correct direction? Turning a reamer backward even a
turn or two, can and will damage the cutting edge. Be certain that
the tailstock is extended far enough so the end of the tailstock
feed screw isn't touching the end of the reamer. Use cutting oil on
the reamer and remove chips often (once it is cutting). Ward
M. (11498) |
| When I first started to ream, I did encounter the problem of
having the reamer bottom out on the tailstock screw, but then
extended the tailstock barrel to avoid this. I'm fairly certain I was
turning it the correct direction (although I've made dumber
mistakes). I got my SB9A from an engineering school lab, I think
it was the one they let the students "learn" on. The tailstock
barrel was pretty well scored up, I'm wondering if the barrel could
have become hardened after misuse? The reamer is brand new, but a
cheap-o import from KBC. I checked it over when it arrived and it
seemed to be in good condition. I'll try the suggestion of
thoroughly cleaning the barrel first, and working from dry to well
lubricated conditions. Tom
(11513) |
WELL LUBRICATED ! Never run reamers
dry. Cutting oil, not waste motor oil. My neighbor uses waste motor
oil for everything. Chain saw bars, weed killer you name it ! but,
do double check the internal taper to make sure there is no internal
shoulder. You can just slide a bar in there and see if it catches on
anything. Also, you didn't mention if you got a finish reamer or the
style you did get. It's hard to see in such a small hole, but when
opening up holes on the Bridgeport, I used to blue the hole to see
if I was actually cutting, and to watch the cutter proceed. if you
blue the hole and try to ream, you might find the high spots. If you
blue the reamer, you'll find out where it is making contact. I'd
look at the very edge of the small taper. Dave
(11518) |
| Reamer question |
| Tonight I
used reamers for the first time. Problem is I need another .001-.002
larger then the 5/16 reamer I have (oversize shaft). Any 'tricks' to
make a reamer cut a little larger? Larry (13788) |
| Don't know trick for making reamer
cut bigger but I think if you use water based coolant instead of
cutting oil reamer will cut "tight". Could you not make pin standard
size? Ron (13789) |
| Yep, pack a
toothpick or what ever in flute and go again. Experiment.
RichD (13790) |
| Don't suppose the oversized shaft is
something you could reduce the diameter of. I have a similar problem
with 1/4" SS shafts that must fit in standard ball bearings, where
there is no option for enlarging the bearing ID, so I polish the
shaft down to fit. Progressive grits of carborundum (silicon
carbide) paper. I use cutting fluid with it too, to help keep the
paper from clogging. Its work, but it works. Rick (13791) |
| Larry, First ream the hole to 5/16. Then put the
reamer through the hole again with a strip of .001 brass shim along
side the reamer. This will enlarge the hole slightly but if still
not enough put it through the hole again with two strips of the
brass shim etc, etc. This method works just fine.
Perry
(13792) |
| I did as suggested and cut the shaft down (Well polished it
down). The reason I hesitated was this is the THIRD crankshaft I've
made for this model and the last thing I wanted to do was give
myself another chance to mess it up. I regained my confidence after
a good nights sleep. I'll use the other suggestions when required
(most probably the next time I need a good fit). Nice to know there
is a way to cheat a little. Larry (13805) |
| You could freeze
the part with dry ice or a dry ice - acetone bath before machining.
You'll have to work fast though because the part will quickly reheat
and expand to its original size. Don't touch the cold part with
exposed skin! Ken
(13808) |
| Taper pin
reamers |
| I am looking for an
online source for taper pin reamers, the hardware stores and home
centers don't have a clue on what they are. Jim (21438) |
| Check out
McMaster-Carr, they will be tapered drills. JP (21440) |
| Tapered drills are
NOT tapered reamers. You can get tapered reamers from MSC. Go to
www.mscdirect.com (21441) |
| Reamers |
| I'm going
to start making a small live steam engine soon. I have been reading
up on making them and have come across the term "reaming" a lot. I do
know it means to drill or bore then use a reamer to get to final
size. What I cannot believe is the different sizes required. Some of
the reamers I have seen called for are out of this world I cannot
believe I will have to buy a full "set" of reamers to have a nice
shop setup. The darn things cost a heck of a lot. I could see one for
maybe the bore of the engine but I read they are calling for reamers
in every hole that has a rotating shaft! Is there some way around
this requirement? Maybe I'm missing something as usual. Tom
(24008) |
| You drill the hole
then use the reamer. Yes good toys are expensive. (24010) |
| Tom , There is no
way around a nice hole. Yes they are expensive. Watch the "imported"
ones from ebay. I bought a 5/8" reamer off a guy and it has so much
runout it would make a nice 7/8" hole. I use 3 and 4 flute drill
bits and sometimes they take the place of a reamer. But they cost
even more than a drill and reamer if bought separate. Also watch the
hole size you just want the reamer to clean up the hole not drill
it. Bob
(24011) |
| Tom, The reamer not
only sizes the hole but it makes it true round, the spiral drill
does not drill true round. If you have shafts running and things
moving, the holes must be round. Paul (24016) |
| You can also bore
the hole straight and true. If it is smaller than your boring bars
can handle get some drill blanks of the size you want and make some
"D-bits" of the sizes you need from them. Most model engine articles
when they discuss reamers, really mean "D-bits". JWE (24017) |
| I do know this stuff is expensive. I have the garage full
of nice stuff and the receipts to show I own them, not just machine
tools either. I do realize the reamer is used after the drill too.
I guess what I am getting at is some of these holes are real
small, less than 1/8" and then the designer would seem to just pick
some value to ream to then you're expected to make the shaft fit the
hole that results. hope that came out ok g size I could work around
that and get the job done. I hope that will work for most small
holes. I also came across some information in another group where
they make their own larger lapping bars from brass and don't ream
the bore at all. A bit of metal polish on the brass rod and hone it
till the walls are pretty smooth. It is after all a model steam or
air engine not a lunar rocket motor g (24019) |
| James, That
is some good advice. I'll have to check around in your groups for
info about "D" bits. What material is it you mean to get to make my
own? I'm not familiar with "drill blanks" but have read some of your
info on the Dbits. Of course I forgot it all g (24020) |
| Tom, Go to McMaster
web site and search for 'drill bit' The drill blanks will come up
along with all sorts of drill bits. The descriptions are very
informative. JP (24021) |
| Drill blanks are
the heat treated shafts that drill bits are ground from. We used
them for axles on our slot cars in 3/32 and 1/8 sizes. JWE (24023) |
| Lapping is an
even nicer way to finish a hole, but I don't know if it corrects for
the uneven hole from a drill. The problem with a drilled hole is
not just the finish, but the concentricity. The shaft going through
may not be straight running, or point where it is supposed to, or may
be touching the hole with only a small amount of surface area (not
good for "free running"). It is all a matter of how accurate and
free running you want your little engine. * the smaller the engine,
the MORE SENSITIVE it is to binding and misalignment, because there
is less power there to overcome the friction caused by these
problems * Try this group:
http://groups.yahoo.com/group/HotAirEngineSociety/ Bernie (24025) |
| Ok I know I have a
lot of Hot Air but do I need a group for it? Sorry I couldn't
resist. I will indeed check them out. I did read they have to contend
with getting their work very close and tight tolerances. Tom
(24067) |
| You have entered
the twilight zone - where the type of fit is critically important to
the ability of the machine to function well. In most other machinery
there is a great surplus of power available to make the parts move,
and overcome all sorts of friction resulting from poor fits ad
surface quality, improper lube, and other gremlins. there are many
choices of materials and methods from which to plan, and there are
freely available variations in all possible sizes. in homebuilt
steam and air engines this is usually not the case. the type of fit
has a great deal to do with how well the resulting joint operates
and how much power it takes to move it. the materials are what they
are and we are not all able to afford the tools, time, and machines
to learn how and then make a microscopic needle bearing lapped to
hundredths so we can make a true scale model. Careful attention to
fitting processes can overcome some of these limitations. The joints
will need flat ( read as polished and true, can be cylindrical as
well as flat in 3-d) and parallel mating surfaces that can maintain
a thin film of thin oil so that the parts can articulate with
minimal actual contact, use low-friction lube, maintain alignment
for good energy transfer, and dint need frequent care or re- lubing.
the joints made this way are then somewhat self-preserving in the
machine and they can endure for a long time. plan on making the
holes using a drill press or mill or maybe a jig boring setup, no
hand held drills. Use proper alignment techniques and tools for all
reaming, lapping, scraping, and polishing work, use marking and
indicating compounds and techniques to get minimal tolerance fits
and to check contact surfaces on articulating parts, and plan on
making a few of them over again once you have learned some lessons.
Its enjoyable to learn this stuff in an environment where you can
approach it with patience. Unless you had a few years to learn at
the side of a real master, there is probably no way to learn to make
this quality of stuff the right way-first time and every time. Its
also greatly convenient to have a very good lighting setup in your
work area (100 foot-candles is NOT excessive) and a fairly good set
of magnifiers like a headset in the 2x-10x range and a few handheld
or mounted devices to let you get a really close and steady look at
things. These are priceless tools for sharpening, hand fitting,
observing surface marks, and finding all kinds of stray burrs and
divots. A steady hand helps but a rest is always better - takes less
practice and makes for less fatigue. one really good cup of tea or
coffee can ruin a steady hand for hours and I for one - WILL have my
beverage when working.
(24082) |
