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Draw bar tightening torque....
It's one of those Micro-Mark mini-mills. I'm tired of beating (albeit
with a plastic head mallet) the bejesus out of the DB to loosen the tapers due to overtightening. Is there a recommended torque for these things. Thanks. |
Draw bar tightening torque....
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Draw bar tightening torque....
What is the spindle taper and what is the tooling in the spindle ?
MT3. End mill holder and drill chuck tapers. No collets. On Dec 16, 9:21*pm, "Terry Coombs" wrote: |
Draw bar tightening torque....
It's the usual Sieg X2 mini mill. I forget whether they sell the
R8 or MT3 version. Micro-Mark sells the MT3 variant. On Dec 16, 9:54*pm, "Pete C." wrote: |
Draw bar tightening torque....
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Draw bar tightening torque....
Get out the torque wrench and do a few tests
Geez, I was hoping someone had done those tests already. Tried to join a Yahoo group supposedly devoted to these Sieg Mini-mills only to find out it's practically dormant. One needs to get permission from the mod to join and I've been waiting for the last two days. Anyway, thanks, guess I'll have to find my own settings. On Dec 17, 9:42*pm, "Terry Coombs" wrote: |
Draw bar tightening torque....
I haven't used one of these machines, but I wonder if your collets are
seating properly. If you start seeing wear marks (changes in the collet surface finish) at the small end and nowhere else along the collet, the collets or the spindle may be out of tolerance. I've never liked rapping on the drawbar to unlock Morse tapers, but it's been done for decades, so it's an accepted practice, although that practice did come from machines weighing 1000s of pounds, not light duty benchtop machines. When the collets don't seat properly, it may take excessive torque to attain a good grip on the cutting tool shank. If the morse tapers don't mate nearly perfectly, some improper wear or distortion is likely to occur. If you're not able to attain a solid grip on the proper size of cutting tool, you may be faced with altering the small ends of the collets to reach the proper gripping force. If the machine is new, you should probably discuss it with a customer service technical person for the seller. A nearly ideal setup might include a lever actuated cam lobe to apply force to the drawbar end, but this isn't particularly easy to retrofit into an existing machine design. Tying to fabricate a big lever-closed clamp-type tool, similar to a engine head spring compressor doesn't sound like a very easy task either. There would probably be too much flexing along the length of the tool to create enough pressure to release the collet. All that you may be able to do is closely examine the surface finish of the collets, and feel the inside finish of the spindle with your fingertips to determine if there are any irregularities. Another possibility could be mis-marked collets. It's possible that some collets actual sizes may be incorrectly marked. You could carefully measure some precision ground parts (unless you have a set of precision plug gages) to see if other sizes are gripped more securely. If the proper size isn't being gripped adequately with a reasonable amount of torque applied (but I don't know what a reasonable amount would be), I'd think there are likely to be some manufacturing tolerances that were exceeded (manufacturing defects), either in the spindle or the collets. -- WB .......... metalworking projects www.kwagmire.com/metal_proj.html wrote in message ... It's one of those Micro-Mark mini-mills. I'm tired of beating (albeit with a plastic head mallet) the bejesus out of the DB to loosen the tapers due to overtightening. Is there a recommended torque for these things. Thanks. |
Draw bar tightening torque....
but I wonder if your collets are seating properly.
No collets. I don't use it very often and changing tooling is even less frequent. A consistent minimum acceptable tightening torque will solve the problem. On Dec 17, 11:38*pm, "Wild_Bill" wrote: |
Draw bar tightening torque....
On Dec 18, 5:42*am, " wrote:
but I wonder if your collets are seating properly. No collets. I don't use it very often and changing tooling is even less frequent. A consistent minimum acceptable tightening torque will solve the problem. On Dec 17, 11:38*pm, "Wild_Bill" wrote: My Emco lathe has a milling head unit that uses Morse #2 collets. It uses a jack bar and a threaded cap to press the collet out. Is your mill adaptable to something like that? Paul |
Draw bar tightening torque....
Maybe the correct tightening torque would be: not quite a full grunt.
I'm fairly sure that starting at a half of a grunt, then trying a little more, would do it. -- WB .......... metalworking projects www.kwagmire.com/metal_proj.html wrote in message ... but I wonder if your collets are seating properly. No collets. I don't use it very often and changing tooling is even less frequent. A consistent minimum acceptable tightening torque will solve the problem. On Dec 17, 11:38 pm, "Wild_Bill" wrote: |
Draw bar tightening torque....
Would you happen to know where a detailed picture of the Emco jack bar can
be seen Paul? I believe any machine that anyone who uses Morse tapers (or any other locking-type tapers) would benefit greatly with the machine modification of a lever release for tooling. -- WB .......... metalworking projects www.kwagmire.com/metal_proj.html " wrote in message ... On Dec 18, 5:42 am, " wrote: but I wonder if your collets are seating properly. No collets. I don't use it very often and changing tooling is even less frequent. A consistent minimum acceptable tightening torque will solve the problem. On Dec 17, 11:38 pm, "Wild_Bill" wrote: My Emco lathe has a milling head unit that uses Morse #2 collets. It uses a jack bar and a threaded cap to press the collet out. Is your mill adaptable to something like that? Paul |
Draw bar tightening torque....
On Sat, 20 Dec 2008 14:24:05 -0500, the infamous "Wild_Bill"
scrawled the following: Maybe the correct tightening torque would be: not quite a full grunt. I'm fairly sure that starting at a half of a grunt, then trying a little more, would do it. I learned this wonderful torque technique when I was wrenching for a living: Step 1: Tighten slowly until you hear and feel the bolt snap. Step 2: Now, QUICKLY back it off half a turn. All done! -- It is pretty hard to tell what does bring happiness; poverty and wealth have both failed. -- Kin Hubbard |
Draw bar tightening torque....
The last time I witnessed a friend snap off a bolt, I remarked: Way to go,
tough guy! Have you been workin' out? Apparently he never learned Step 2. A mind is a terrible think to waste. -- WB .......... metalworking projects www.kwagmire.com/metal_proj.html "Larry Jaques" wrote in message ... On Sat, 20 Dec 2008 14:24:05 -0500, the infamous "Wild_Bill" scrawled the following: Maybe the correct tightening torque would be: not quite a full grunt. I'm fairly sure that starting at a half of a grunt, then trying a little more, would do it. I learned this wonderful torque technique when I was wrenching for a living: Step 1: Tighten slowly until you hear and feel the bolt snap. Step 2: Now, QUICKLY back it off half a turn. All done! -- It is pretty hard to tell what does bring happiness; poverty and wealth have both failed. -- Kin Hubbard |
Draw bar tightening torque....
"Wild_Bill" wrote in message ... Maybe the correct tightening torque would be: not quite a full grunt. I'm fairly sure that starting at a half of a grunt, then trying a little more, would do it. -- WB ......... metalworking projects www.kwagmire.com/metal_proj.html wrote in message ... but I wonder if your collets are seating properly. No collets. I don't use it very often and changing tooling is even less frequent. A consistent minimum acceptable tightening torque will solve the problem. On Dec 17, 11:38 pm, "Wild_Bill" wrote: For us in the metric world ,do you have a metric equivalent of 1 grunt? |
Draw bar tightening torque....
" For us in the metric world ,do you have a metric equivalent of 1 grunt? 1 grunt = 3.67 centiheaves ** Posted from http://www.teranews.com ** |
Draw bar tightening torque....
I'm afraid that the metric equivalent of Grunt conversion would involve
calculating fig newton pied du roi (not to be confused with cor du roi), which I'm unfamiliar with, but I believe is included in the French version of Machinerys Handbook. They use it frequently in bicycle design. -- WB .......... metalworking projects www.kwagmire.com/metal_proj.html "Grumpy" wrote in message . au... "Wild_Bill" wrote in message ... Maybe the correct tightening torque would be: not quite a full grunt. I'm fairly sure that starting at a half of a grunt, then trying a little more, would do it. -- WB ......... metalworking projects www.kwagmire.com/metal_proj.html wrote in message ... but I wonder if your collets are seating properly. No collets. I don't use it very often and changing tooling is even less frequent. A consistent minimum acceptable tightening torque will solve the problem. On Dec 17, 11:38 pm, "Wild_Bill" wrote: For us in the metric world ,do you have a metric equivalent of 1 grunt? |
Draw bar tightening torque....
The French version unfortunately only contains data on reverse gearing.
"Wild_Bill" wrote in message ... I'm afraid that the metric equivalent of Grunt conversion would involve calculating fig newton pied du roi (not to be confused with cor du roi), which I'm unfamiliar with, but I believe is included in the French version of Machinerys Handbook. They use it frequently in bicycle design. -- WB ......... metalworking projects www.kwagmire.com/metal_proj.html "Grumpy" wrote in message . au... "Wild_Bill" wrote in message ... Maybe the correct tightening torque would be: not quite a full grunt. I'm fairly sure that starting at a half of a grunt, then trying a little more, would do it. -- WB ......... metalworking projects www.kwagmire.com/metal_proj.html wrote in message ... but I wonder if your collets are seating properly. No collets. I don't use it very often and changing tooling is even less frequent. A consistent minimum acceptable tightening torque will solve the problem. On Dec 17, 11:38 pm, "Wild_Bill" wrote: For us in the metric world ,do you have a metric equivalent of 1 grunt? |
Draw bar tightening torque....
Keywords:
In article , "Wild_Bill" wrote: I'm afraid that the metric equivalent of Grunt conversion would involve calculating fig newton pied du roi (not to be confused with cor du roi), which I'm unfamiliar with, but I believe is included in the French version of Machinerys Handbook. They use it frequently in bicycle design. I thought the French version was: un grunte conversion factors: How many oomphs to a grunt? Doug White |
Draw bar tightening torque....
"Bill Noble" wrote in message ... " For us in the metric world ,do you have a metric equivalent of 1 grunt? 1 grunt = 3.67 centiheaves ** Posted from http://www.teranews.com ** Thank you Bill. That was the conversion factor I needed |
Draw bar tightening torque....
On Dec 24, 6:17*pm, "Grumpy" wrote:
"Bill Noble" wrote in message ... " For us in the metric world ,do you have a metric equivalent of 1 grunt? 1 grunt = 3.67 centiheaves ** Posted fromhttp://www.teranews.com** Thank you Bill. That was the conversion factor I needed With a #3MT I'd begin by torquing to 20 ft-lbs, and see how it goes. Due to size restrictions on my mills I use collets exclusively for endmills... My vertical and horizontal mills have #2 and #3 MT respectively, and the #2 is quite hard to release without the jacking arrangement supplied by Emco Maier. Strangely the #3 MT is fairly easy to release, a sharp whack with an aluminum rapper and it is loose. The #3 MT collets were imports bought from Busy Bee in Canada. While the tapers are OK some of the bores were a few thou. oversized. With these I use a sleeve bent up from appropriate thickness shim stock... The complete set of #3 MT collets from 1/8" to 3/4" cost less than $80 20-odd years ago and I didn't quibble about this defect. The vertical head for the H-mill has a taper I was never able to identify. The large end is about .025" larger in dia. than a #2 MT and with a different taper/inch. I tried B&S #7 but no joy. Finally I machined a batch of collets and shanks from 4140 to solve that problem. However, this taper is an absolute bear to release. I used an aluminum rapper and one project where I had to change cutters often my hand got really sore. Didn't improve the bearings, either; they now require replacing. I solved the releasing problem by changing the draw bar, a grade 5 3/8-16UNC hex head bolt 7" long, into a jacking-type draw bar. To do this it is necessary that the draw bar hole in the spindle be significantly smaller than the small end dia. of the taper, ie. a step is required from the bottom dia. of the taper bore to the draw bar hole. Further, the taper bore must be at least 1/2" deeper than the reach of the small end of the collet. By fastening a sleeve to the draw bar such that it bears against this step while unscrewing it, a jacking action is produced that pushes the collet from the spindle taper. Considerable torque is required to push out the collet... I use two wrenches, one on the draw bar and one on the pre-load adjusting nut (really two nuts torqued against each other). Of course the cutter drops out of the collet, but I place a block of wood on the table to prevent this. This system works quickly and easily and I can recommend it strongly where it can be retro-fitted. Wolfgang |
Draw bar tightening torque....
With a #3MT I'd begin by torquing to 20 ft-lbs
Finally settled with 5 ft-lbs. Even 10 ft-lbs required too much whacking to loosen the tapers. On Dec 24 2008, 7:51*pm, wrote: |
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