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| Proxxon PD400 |
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| spuddevans:
--- Quote from: andyf on January 05, 2012, 06:58:19 PM ---Wong, changing the subject line doesn't seem to have worked. --- End quote --- Now fixed. Tim |
| wongster:
Thanks Tim. |
| andyf:
Hi Wong, It's been 50 years since I bumped into trig, so I use this http://www.cleavebooks.co.uk/scol/index.htm If you click on Sectors, your measurement will be the chord and the angle will be either 120 or 90, depending whether you have 3 bolts or 4. That will give you the radius, which should be doubled for the PCD. I think clearance is allowed in the holes in the spindle flange to ensure that the register locates the chuck, without being influenced by any tiny errors in the positions of the bolts or the holes. My lathe came with M8 bolts and 9mm holes. Andy |
| Fergus OMore:
SomehowI suspect that you are expecting too much in the way of accuracy from your lathe. Initially, you set off with problems with stiff handles or dials and came up with a question about the fit of a pair of sliding parts- and then came up with a solution of - Using grease! Sorry but the correct lubricant for sliding parts is slideways oil or even ordinary motor oil-- but not grease. Again, you did this 'improvement' with the feed screws. Sorry, the slides are always done by removing the feed screws, oiling and feeling them slide - to suit your way of working. Then, the feed screws and nuts are replaced- and tested again for stiffness, backlash and so on. If, as others and yourself mentioned, there was some doubt about fit and 'faked' scraping, you should have blued the matting parts in- and got a scraper out and got them to fit. You may have had to scrape the gibs or even had to peg them- but you would have a nicely adjusted lathe. This would have given you a lathe which would be nice to quickly clean at each maintenance session. Because this is what everyone has to do-- or should do! Let us turn to three jaw chucks now. Few lathes possess chucks which are really accurate. You can expect them to hold perhaps 0.003" TIR but to get better, you involve greater expense in having to get something like a Griptru. If you cannot afford one, then you use a independent four jaw or perhaps collets if the work is small enough. Now, you have some difficulty in fitting retro-fitting a three jaw backplate. Initially, the backplate should be machined to get an accurate face and then addressed to take new chuck. As the chuck is going to have an element of inaccuracy, you should clock - not on the jaws but on the outside of the chuck body- and after all the mechanism has been removed- and everything ready and cleaned. The bolt holes or tappings follow and only after the lot has been de-burred, assembled. As far as the collets are concerned, you only get what you pay for. Above all, you should check your own work- step by step- and make each correction and adjustment as you go along. I have no doubt that others will find room to criticise these comments but it should suffice to say that I run an very old Myford Super 7 which had been abused and used on woodwork. The bed was re-ground professionally and the fit of the saddle had to be re-built with Turcite. The smaller items were scraped in by hand and the things like broken and sheared gears were machined and fitted. Unashamedly, this is not perfect and some parts could do with replacing but there is always difficulty in getting spares- or finding time to make them. I hope that my comments might be of some use to you. |
| wongster:
Thanks for your comments. It is helpful. In fact, I'm not expecting anything as I don't know what's too much or within norm. I do property loans for a living in a bank. No background or any training in mechanical stuff. Like many others, this is a hobby. I'm learning as I go. After reading the post on using way oil, I wiped off the grease and use the way oil I bought from A2Z CNC. I wanted to remove the feed screws but that seem impossible; one side has a key for the handwheel that blocks coming out from that direction and the other side is blocked by the shoulder (may be using wrong term here) of the feed screw). Same arrangement for both the compound slide & cross slide. I wonder how they put that in in the first place. I'll look at them later tonight. I don't think I know and am confident enough to scape. I believe with my current level of knowledge (or lack of), the part will no longer be usable. I'll start looking at scraping when I get my basic out if the way. The ER32 was mentioned because I've full set of the collets bought something back. The ER32 MT1 chuck I bought from US has too great a runout to be of good use. I kind of like the use of the ER collet than the 4 jaw chuck. This is from the prospective of a beginner. Keep your comment coming. Regards, Wong |
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