Crawford Trugrip 5C collet chuck issue

As per the title, I've had an early Trugrip chock for ages, but never really used it because it was set up for the rather strange left hand thread collets which seem to be made of Unobtanium. Having fitted a 5C (conversion) plate in the rear of the chuck, I was hoping to be able to use the chuck on my DSG lathe with the large connection of 5C collets I have that fit in the spindle of another lathe of mine. The issue I now have is that the collet register has sheared off at some time in the past making it very difficult to load a collet securely.

The sheared key is visible in the photo above.

The photo below shows the partially stripped chuck from the front. It looks pretty clear to me that the ring with the sheared key needs to come out the replace the key/register, but it isn't clear how to remove it. Some exploratory blows with a hammer and brass drift didn't cause any movement trying to tap it out the back.

If anyone on here has some experience of stripping one of these chucks, I'd really welcome some suggestions.

It looks like it may just need knocking out from behind (below in the picture orientation), the slot looks like it may be tapered. A key like that will get some wear and tear in regular use so it should be a simple job to replace it.

Martin C

You can get TruGrip collets easily enough, they are not made Unobtainium any more but are now made of Expensivium! Just ask Home and Workshop in Sidcup or look on a well known auction site.

Had a quick look on ebay, Metric Trugrip collets 30 something quid each! what happens if you need hexagonal or square collets -these are easily available in 5C and while they're more expensive than round hole ones, I've never come close to paying 30 quid each for them.

Still struggling with the key/register issue, have tried knocking out the sleeve with a brass drift again. I will try using my hydraulic press later on, but it's awkward to set the press mandrel to get a straight push.

Why don't you take the pinions out just to make sure there's nothing holding it in place there

Solved! Took a very long look at the chuck after my last post. I have always wondered why there was a kind of collar on the front of the chuck. So, I put the chuck in my hydraulic press with the mandrel pressing against the rear centre portion of the chuck. Mine is a 30 ton press, but I hadn't got it pumped right up before the tapered piece came out with a huge bang.

Here's the chuck the other way up, I've removed the sheared off key/register the remnant is sitting on top of the chuck in the second photo.

When I get a bit of free time, I'll turn a new one from a piece of EN8; the remnant is 1/4" long, I'll make the new one 3/8" long and hopefully I won't need to repeat the repair in the future.

Edit, inserted missing second photo

Edited By Stueeee on 09/05/2023 20:56:07