Hi

I want to see if my intuition is right. When fitting a chuck back adapter – the kind that registers with a diameter and bolt circle – it seems that the part that is touching should be where the bolt circle is, while the other diameter shouldn't touch at the back.

So far I've only seen chucks where the bolt circle was outside the register diameter, so the parts touching were the outside and the register was… registering… but not touching at the back.

I now have a chuck with the bolt circle inside the register, so I think the register diameter should both register and touch at the back, with the outside diameter not touching. My impression is the outside diameter touching at the back first could distort it (i.e. with a gap where the bolts are). The bolt circle is relatively small in this case and the back touching on the outside diameter seems more rigid, but it's not like the bolt circle is tiny. The chuck is probably not going to distort either way… or…?

Am I right?

Thanks!

Edited By Nitai Levi on 29/11/2016 05:48:55

Thanks, though I'm not sure I completely understand what you said or if my question was clear. The register diameter centering the parts and the bolts not centering anything is clear.

If I understand, you mean the chuck and adapter should always touch at the back in the larger diameter on the outside, regardless of whether the bolts are inside or outside the register diameter? Or maybe that the back should touch wherever the bolts are not? Since they are sometimes inside the register diameter and sometimes outside.

On the chucks and adapters I have, the bolts are outside the register diameter, like this (example from Google, with relatively small area outside the register). The register on the adapter is a little shorter than the same on the chuck, only used for centering and some angle alignment, with the outside touching each other to also help with angle alignment.

Here is the opposite extreme, with the bolts all "squished" in the center, inside the register

On the chuck I'm considering it's more or less like this, with the bolts still inside the register diameter. It looks to me like it would be better to have the register touching at the back too. The corners will be "broken" so there is no interference in that way. Is it still better to have the back touch on the (pretty small) outside? This puts force like a lever between the inside area and outside area of the chuck. I don't know what would give first, but I'm guessing the chuck would bend slightly before a screw or part would break… The other way around would eliminate that, the question is only whether this would be less rigid because the outside of the chuck isn't touching at the back.

Edited By Nitai Levi on 29/11/2016 09:33:02

If I understand, what you're saying is that for a chuck like I'm considering, with a relatively large register (compared with the chuck diameter) and bolts inside the register, the back should still touch at the larger diameter outside the register, with a slight gap where the bolts are, even though this creates a "lever" between the register diameter and larger diameter essentially trying to bend the chuck/plate.

So my question is… why? What problem is caused by having the register diameter touching both radially and axially? Why is this worse than the "lever" issue? Basically whatever the better option is, I'm trying to understand why.

Thanks again!