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| Tapering & reducing the diameter of rod - Help Please |
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| JigGuy:
Hi Everyone, First post here... I wasn't sure where to to post this & your forums look helpful so here goes. I am trying to figure out how to reduce the diameter of the last 2 inches of a 32 inch rod from .375 dia to .345 or so. I should add that I am working with plastic (I know there are a lot of metal machinists here sorry ;-). If the end could be rounded or tapered that would be a bonus. Here is what I have come up with so far (I am helping my father with a prototype in his garage.. I am not a machinist). 1) I could try to use a belt sander but I cant seem to keep it uniform all the way around 2) I have looked at cylinder/drum sanders but cant seem to find one long enough http://duragrit.com/us/tools/popups/sr-ht2.html 3) This is close to what I am looking for but I would need it to be 1.5 inches longer http://www.widgetsupply.com/page/WS/PROD/dremel-grinding-stone/BBL04 Does anyone know of a bit or jig that would enable me to be able to put the end of the rod in & have some of it shaved/sanded off (like a router would do but from the outside)? I hope my question makes sense, its getting late & thought I would post after endlessly searching for a solution. Any help or input is appreciated (I should add the quieter the solution the better as he is in a townhouse & the neighbors are not fans of our noisy garage shop fun haha). Thanks again, I appreciate it ;-) |
| Bluechip:
Depending on the 'plastic' I would suggest any attempt at abrasive removal would result in a heat-welded mess. You don't say where you're from but maybe if this post was was in the 'Work Wanted' section, some one local to you MAY poke it in his lathe and do the job in some 2 mins ?? BC |
| JigGuy:
Thanks BC, I am actually from Vancouver, BC Canada. We have ground this plastic rod without any melting in the past (I have sanded it & put it on a grinding wheel). The challenge is making it uniform all the way around. We may need more than a one off if possible & trying to avoid custom rod prices if at all possible. Thanks again, I appreciate the input. |
| andyf:
If the dimensions are not too critical, I reckon it could be done with an electric drill (corded or cordless, but with variable speed so you can run it slowly), a file and some way of supporting the rod. For the supports, make up a baseplate with two uprights, about 2.25" apart, each with a 3/8" hole in it. Start with just over 33" of rod, and pass it through the holes so it will rotate. Power the rod's outer end with the drill, and use a file followed by emery paper (and then metal polish if you need a smooth surface) to reduce its diameter between the uprights. Once you have got it down to your "0.345" or so", cut the unwanted bit off the end so you are left with 2" of the reduced diameter. Some lube in the crude 3/8" bearings would help, and might stop them marking the plastic too much. But oil or grease sometimes makes wood swell sightly, which might cause binding, so if you use wooden uprights, a wax-based furniture polish might be a better choice. If you can find some aluminium say 1/2" thick, that would be a better option for the uprights, though it might involve you in unwanted metalwork in fastening the uprights to the base. Andy |
| BiggerHammer:
Apologies for my following bit of stupidity. If a short length of bevel would work I would say stick it in an old fashioned crank pencil sharpener (one that works with the BIG kindergarten pencils) give it a few cranks then polish/file to desired surface finish. I have a silly idea for reducing the diameter also. Let me see if I can figure out a drawing program and I will post something. (don't hold your breath on that though) |
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