ER collet adapter

[RedpiperbobParticipant @redpiperbob16487]

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

[RedpiperbobParticipant @redpiperbob16487]

[bernard towersParticipant @bernardtowers37738]

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.

[JourneymanParticipant @journeyman]

Glad you got the problem sorted. Hope the "Mandrill" didn't get too stroppy:-

They tend to get a bit grumpy . On the other hand a mandrel is usually OK with being used to support a job on the lathe or being hammered on! The lathe spindle on the other hand does not appreciate being used to form sheet metal but the spindle nose is quite alright about having chucks screwed to it.

( Apologies in advance for any distressed feelings but couldn't miss the photo opportunity! )

John

[RedpiperbobParticipant @redpiperbob16487]

Damn Microsoft spell checker

Bob

[old martParticipant @oldmart]

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.

[AdrianRParticipant @adrianr18614]

Possibly as colourful as Bob's language when he found the problem

Adrian

[Howard LewisParticipant @howardlewis46836]

That's what happens when you start to monkey about with things!

Howard

[CHARLES lipscombeParticipant @charleslipscombe16059]

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

[RedpiperbobParticipant @redpiperbob16487]

Hi Chas thats what I have been doing up until this purchase.

Bob

[Michael GilliganParticipant @michaelgilligan61133]

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 BlokeParticipant @kiwibloke62605]

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.

[RedpiperbobParticipant @redpiperbob16487]

well they pulled mine off

[Kiwi BlokeParticipant @kiwibloke62605]

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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