8 inch 4 jaw Chuck on WM290 lathe?

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8 inch 4 jaw Chuck on WM290 lathe?

This topic has 31 replies, 13 voices, and was last updated 16 February 2021 at 21:13 by Adan Santander.

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15 February 2021 at 21:29 #527603
Adan Santander
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@adansantander89729
I thought I would update for anyone looking for the same answers than I was.

I have made the back plate in AL 2014AT6.

It weights just over 2Kg. The studs are threaded in blind tapped holes. According to Umbrako Engineering Guide tables, AL has more thread stripping strength than Cast Iron.

The chuck can open the jaws to full extend without any problem.

Stopped…

In short:
- The chuck seems all right in the lathe. Rather heavy item. Not an everyday chuck but worth having it for those large parts. Weight does not seem to be a problem for the motor or bearings. Nonetheless, I would happily had the light duty version of the chuck and save several Kg; handling would be much easier.
- The aluminium plate is fine and saves weight. It will stand any stress from normal use, however it will not be happy with dings. Careful handling when mounting and un-mounting to protect the registers from hits and it should last. I am using aerospace grade AL. This is used in engine parts and rotors.
Edited By Adan Santander on 15/02/2021 21:29:23
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16 February 2021 at 13:31 #527730
Thor 🇳🇴
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@thor
Hi Adan,

Well done, you can now machine large work on your lathe.

Thor
16 February 2021 at 15:38 #527762
old mart
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@oldmart
Good result, your backplate will do its job perfectly. Make sure the studs and nuts are high tensile. If you ever worry about the threads in the aluminium, then helicoils would address that.
16 February 2021 at 15:45 #527767
Tony Pratt 1
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@tonypratt1
Posted by old mart on 16/02/2021 15:38:16:

Good result, your backplate will do its job perfectly. Make sure the studs and nuts are high tensile. If you ever worry about the threads in the aluminium, then helicoils would address that.

Good point, but I know for a fact the OEM studs in my Warco WM290V are 'low tensile' Chinesium steel but then again I haven't gone large on the 3 jaw chuck.

Tony
16 February 2021 at 16:10 #527775
Adan Santander
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@adansantander89729
@Old Mart, thank you. Yes, I am using HT grade 12.9. Perhaps a bit too much since I cannot apply the required tightening torque.

I have a doubt regarding using helicoils in aluminium that you may help me with. I fully understand the use of helicoils, but how would it make the thread stronger in a material? At the end of the day, it just presents a thread to the interface; wouldn't it be also susceptible of wearing the thread in the tapped hole. Is it just that it uses a 'bigger' thread? Or the fact that it is not removed once and again…?

Edited By Adan Santander on 16/02/2021 16:11:30
16 February 2021 at 20:59 #527877
old mart
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@oldmart
A helicoil is a diamond section steel, or stainless steel coil which requires a larger thread in the base metal than standard. It is the larger thread which gives more strength. Almost all aircraft threads in aluminium and magnesium have helicoils in them and many steel parts also. The thread is stronger, tougher, and has a couple of added bonuses. The coil is easy to replace if necessary, and the coil can be made self locking. If your alloy is a good one, then 2 diameters of thread used will be plenty for your lathe. From the pictures, 2 diameters or more is easy to achieve, without needing the coils.
16 February 2021 at 21:13 #527883
Adan Santander
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@adansantander89729
@Old Mart, Thank you very much for the wisdom.

I have indeed tapped 21 mm in the flange. The screws are 10 mm diameter.
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