Myford ML7 Chucks - Which one?

So to complete the thread - I tried the chuck in all three backplate positions, and tightening all three pinions a couple of times for each position. In the end I’ve ended up with consistently around 0.0005” runout with the best pinion in the best backplate position.

Good choice. I have the same chuck. Got mine from Myford.co.uk. They supplied a backplate too. I went with the one with the dividing holes. Never used them, but it'll be future proof if I want to use them in the future.

Re chuck removal, I have a large diameter Hex bar which I secure in the chuck, then use a spanner on it to loosen, after engaging the spindle lock on my Myford Super7. Works quite well for me so far with no issues.

So to summarise, great chuck. Slightly pricy from Myford, but I wanted to support a British company. Even if they're not fully made here any more!

I admit that’s what I thought - made (or supplied!) from just up the road, and ‘reassuringly expensive’. Right or wrong I’ve got it, and it seems fine. A few burrs on the peripheral machined ring, but there we go.

I went for the Arc back plate based on looks alone - it seemed much better finished. I considered the Myford/RDG drilled version, but couldn’t really think I’d ever use it. As I said, the Arc backplate was pretty tricky to machine - lots of tool grabs even with new inserts. Tried all speeds too. Anyway, it’s done.

Well worth trying all 3 backplate positions and pinions, with different test piece positions at each setting. I was amazed at the difference in runout. I would never have known without this thread.

Be aware that one of our reputable suppliers is being honest about some lower quality chucks they are selling at a reduced price. This reminds us that chucks are just mass produced, tested, and the poorer ones sold off cheap but not marked up as secod or thrid rate. These are then sold by various barrow-boys who will not declare the deficiencies.

So if you get a new chuck off ebay from a non-mainline supplier check it immediately for concentricity with several sizes of stock. If the error is >5thou and moves around the chuck at different work sizes it is a substandard one and it is not the jaws or the backplate but potentially the scroll. Don't accept an 'exchange' from them as all their stock will be the cheap ones.