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| Making an accurate spindle with an innacurate chuck. |
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| S. Heslop:
I've spent the last 3 days trying to solve this problem and everything has failed, so i've given up on trying to figure out a solution on my own. I'm making a 250mm extended spindle that screws onto the end of a tile saw motor. This probably wasn't the best way to go about the problem but i've been trying to build this thing in a way that doesn't depend on a lathe (even if I was using one for convenience), but with the huge spindle wobbling the whole thing vibrates too much. There's a shoulder on the motor that's accurate enough that i'm trying to register the spindle on to, but I figure my problem is that my 4 jaw chuck is too wobbly. I was reading a 0.10mm wobble over 90mm of the bar. Here's the offending chuck. The bar diameter is too large to fit on the smaller 3 jaw that came with the lathe. So far I've tried shimming the part in the chuck (i don't have any shim material thin enough), grinding the chuck jaws (I did it very carefully and very slowly, marking the jaws with a pen and feeding so fine that i'd only see about 1 spark per pass, which then increased that wobble to 0.12mm wobble over 90mm), machining an aluminium 'collet' in the 4 jaw chuck (which I really thought would work, but the bar wobbled more still). I have checked with other ground bars so I don't think the bar i'm using is bent. I'm really stumped so any suggestions would be appreciated. |
| Fergus OMore:
Taking the shortage of shims bit, I would suggest that you have a thous or so in the toolmakers traditional tool- cigarette paper. Again, you can use aluminium oven foil or cut up drinks cans. I like the drinks can one :beer: I would, however, not go down the 4 jaw route but traditionally work between centres in spindle making. Basically, this means that you can pull the lot out and measure or whatever and get it all back together accurately and without too much effort. Others may disagree but you will find that many motor spindles are 'popped' so that commies etc can be skimmed. You'll obviously need some method of centreing a centre and having a driver and either a catchplate or faceplate. Probably you could 'fiddle' a bit by using a three jaw chuck to hold a bit of bar, centre it and put a ball bearing in between the female centres. By the way, I'm assuming that you haven't got a lot of accessories. Regards Norman |
| S. Heslop:
--- Quote from: Fergus OMore on November 20, 2013, 03:51:51 PM ---Taking the shortage of shims bit, I would suggest that you have a thous or so in the toolmakers traditional tool- cigarette paper. Again, you can use aluminium oven foil or cut up drinks cans. I like the drinks can one :beer: I would, however, not go down the 4 jaw route but traditionally work between centres in spindle making. Basically, this means that you can pull the lot out and measure or whatever and get it all back together accurately and without too much effort. Others may disagree but you will find that many motor spindles are 'popped' so that commies etc can be skimmed. You'll obviously need some method of centreing a centre and having a driver and either a catchplate or faceplate. Probably you could 'fiddle' a bit by using a three jaw chuck to hold a bit of bar, centre it and put a ball bearing in between the female centres. By the way, I'm assuming that you haven't got a lot of accessories. Regards Norman --- End quote --- The trouble is is that I need to bore the end of the bar, so that rules centres out. In all honesty i'm not even that convinced my lathe bedways are level. The lathe has been neglected since I bought it, but i've been holding off adjusting it all till I can afford a milling machine. I am sort of short in terms of accessories. I did think that a steady rest might help keep the bar parallel to the ways but I'm also short in terms of money. I could attempt making one but without a milling machine it'd be a whole project in itself. I could maybe try cigarette papers but it was such a fiddle trying to fit the pop can shims in that I'd rather avoid that unless I was sure it'd eventually work. They might still be too coarse. |
| Stilldrillin:
Steve (?). You really need a fixed steady, for that job. Though, I'm sure someone else will disagree...... :thumbup: David D P. S. Amadeal, £19...... http://www.amadeal.co.uk/acatalog/Fixed_Steady__Rest.html |
| S. Heslop:
--- Quote from: Stilldrillin on November 20, 2013, 04:15:52 PM ---Steve (?). You really need a fixed steady, for that job. Though, I'm sure someone else will disagree...... :thumbup: David D --- End quote --- I'm Simon! I'm just not used to the idea of signing posts, it's really frowned on on some forums. Internet etiquette is a funny thing. I'm looking at the prices of fixed steadies and at ~£30 I may as well buy one. There have been a few jobs in the past where i've wished I had a steady as well. Now I just need to decide which shop I want to order from. |
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