Backplate Material

[ddickey]

I'm making another ER chuck for the lathe and will be making my own backplate. Previously I used 12L14 I think. I know cast iron is the preferred choice. I never really noticed any issues with the 12L14.
Any opinions on what material?
I'll be making the collet out of A311 Stressprrof.

 

[darkzero]

I don't think it matters really for a cam lock spindle or other taper nose spindle. I've always made my backplates out of cast iron as that seems to be the norm but really only cause blank back plates come in cast iron.

I believe backplates were usually made out of cast iron to prevent thread galling on threaded spindles (and cheaper). The D1-4 backplates on both my Bison chucks are steel.

 

[ddickey]

That surprises me that your Bison backplates are steel.

 

[darkzero]

Why?

They're the fully machined backplates for the forged steel body Set-Tru chucks. I believe all their plain back chuck backplates are cast iron.

 

[savarin]

Made a threaded backplate for my 4 jaw from some hot rolled mild steel plate with a boss welded on.
Hasnt been a problem so far.

 

[ddickey]

I used a box tool . One pass to make this part.

View attachment 290123View attachment 290123

Why?

They're the fully machined backplates for the forged steel body Set-Tru chucks. I believe all their plain back chuck backplates are cast iron.

I know there are forged steel chucks but I guess I thought the backplates were all cast iron.

 

[Dabbler]

All of the Pratt Bernerd backplates I've ever seen, including the threaded ones have been steel.

Possibly the only reason to use cast iron is tradition and cost. People tell about galling and repeat it because they think it's true, but it isn't. The only materials that gall on themselves are stainless steel and Titanium in the softer grades. If steel on steel galls then every nut and bolt would have a problem.

12L14 is more than adequate for a backplate.

 

[projectnut]

Cast iron is the "preferred choice" because of its vibration absorption and dampening capacities. That being said I doubt you'll have troubles using 1018, 12L14 or any other similar material. Over the years I have made at least a dozen back plates. I've used 1018, 12L4 cast iron, and even "mystery metal. They all work fine and none has had a vibration problem.

As a side note the cast iron ones were the nastiest to fabricate. Cast iron generally machines off as dust rather than chips. It gets into everything and is difficult to remove. I had to machine a number of cast iron castings years ago. Some of the dust was so fine it got imbedded in my hands. It looked like my hands were rusting for nearly a week. Now when taking more than a few small cuts I wear nitrile gloves

 

[ddickey]

Yeah that's one of the reasons I wanted to avoid it.