Redpiperbob | 23/05/2020 11:03:36 |
![]() 92 forum posts 41 photos | Hi there I thought this information might be useful to others. I recently bought an ER20 collet adapter for my Myford Super 7 lathe from RDG Tools. The box contains a threaded adapter for the lathe mandrill, a collet body and a collet nut. What you are supposed to do is screw the adapter to the lathe mandrill then turn down the boss of the adapter to match the collet body (I also put a small relieve at the base of the register). I then screwed the body to the adapter and measured the run out. I was getting 12 thou runout. I took the collet body off and measured the register it had less than half a thou runout. I then refitted the body but did not fit the screws supplied with the kit. No runout. I then tightened the screws (carefully) and I got the 12 thou runout again. I then got three screws from my stock and fitted them, no runout. I then looked at the screws that came with the kit and noticed that the heads were not parallel with the threads. I throw them out. Job done and now less than .5 of a thou runout. I just thought this maybe useful to someone else. Bob |
bernard towers | 23/05/2020 11:32:06 |
1221 forum posts 161 photos | Just goes to show you get what you pay for even in fasteners. I machine a lot of stainless socket heads for HD’s as in the supplied state the heads can be up to 20 thou eccentric!! It would never have occurred if they had supplied Unbrako’s. |
Journeyman | 23/05/2020 12:01:41 |
![]() 1257 forum posts 264 photos | Glad you got the problem sorted. Hope the "Mandrill" didn't get too stroppy:- They tend to get a bit grumpy ( Apologies in advance for any distressed feelings but couldn't miss the photo opportunity! ) John |
Redpiperbob | 23/05/2020 12:14:16 |
![]() 92 forum posts 41 photos | Damn Microsoft spell checker
Bob |
old mart | 23/05/2020 14:00:59 |
4655 forum posts 304 photos | If somebody posts a picture of the other side of the mandrill, it will be just as colourful. Leaving a bit of play in the register and the screw holes gives you the option of getting everything running perfectly, even if one of the collets is less than perfect. With an eccentric collet, you would have to re align every time it was used as there is no way of indexing the collets in the holder. |
AdrianR | 23/05/2020 17:17:59 |
613 forum posts 39 photos | Possibly as colourful as Bob's language when he found the problem
Adrian |
Howard Lewis | 23/05/2020 17:22:49 |
7227 forum posts 21 photos | That's what happens when you start to monkey about with things! Howard |
CHARLES lipscombe | 24/05/2020 05:28:09 |
119 forum posts 8 photos | A bit off-topic but tip I picked up from another post - use a Stevenson's collet block mounted in a 4-jaw chuck. The amount of time and trouble this idea has saved me is incredible. It is also a lot cheaper than some of the alternative collet holding devices out there Chas |
Redpiperbob | 24/05/2020 07:45:59 |
![]() 92 forum posts 41 photos | Hi Chas thats what I have been doing up until this purchase. Bob |
Michael Gilligan | 24/05/2020 08:35:21 |
![]() 23121 forum posts 1360 photos | Posted by Redpiperbob on 23/05/2020 11:03:36:
[…] I then looked at the screws that came with the kit and noticed that the heads were not parallel with the threads. I throw them out. Job done and now less than .5 of a thou runout. I just thought this maybe useful to someone else. Bob . Thanks, Bob ... It tells us a lot but I’m not going to labour the point. MichaelG. |
Kiwi Bloke | 24/05/2020 10:15:55 |
912 forum posts 3 photos | Perhaps I'm being a bit thick, and have missed something important, but I would expect this set to be designed so that the collet body is kept in radial alignment by a register on the adaptor. I'd expect the user to have to turn the register's diameter down to size, and also to face the adaptor. Then, surely, even 'wobbly' screws - if they fit the holes - will not derange alignment. |
Redpiperbob | 24/05/2020 10:32:31 |
![]() 92 forum posts 41 photos | well they pulled mine off
|
Kiwi Bloke | 24/05/2020 10:43:45 |
912 forum posts 3 photos | I'm not doubting your observation, but I'm struggling to understand how. [I like to understand things - it's a failing...] The supply of obviously defective screws with the kit would raise my suspicions to danger level, and I'd be going all over the thing with an impressive array of metrology gear. Or wondering whether to return the thing... Edited By Kiwi Bloke on 24/05/2020 10:47:45 |
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