D1-5 Backplate

[thestelster]

I recently purchased an Accusize D1-5 backing plate to install on a new 6" 4-jaw chuck, which I haven't bought yet.

This backing plate is 1.820" thick, not including the 1/8" flange.
Checking online for other manufacturers dimensions for comparison:
Bison: 1.350"
Atlas: 1.125"

Is there any reason I need to keep it so thick? Should I use it as is, or face it down to Atlas or Bison dimensions?

Maybe the Accusize plate was designed for Set-Thru style chucks?

 

[Dabbler]

Maybe the Accusize plate was designed for Set-Thru style chucks?

It allows you to mount either style. For a D1-5 I'd leave at least a 1/2" full diameter in any event. Some collet chucks need a deeper backing plate, so they have covered all the bases, at the cost of shipping$$

 

[thestelster]

It allows you to mount either style. For a D1-5 I'd leave at least a 1/2" full diameter in any event. Some collet chucks need a deeper backing plate, so they have covered all the bases, at the cost of shipping$$

Hi John, what do you mean,
"... leave at least a 1/2" full diameter..."

 

[Susquatch]

Is there any reason I need to keep it so thick? Should I use it as is, or face it down to Atlas or Bison dimensions?

I had thought your lathe was D1-6 not 5. I'm a bit surprised at that. Mine is D1-5.

Accusize sells several different back plates. I believe the thick one like yours is steel and the thinner one is cast iron. I have at least one of each. I like the thicker steel one like yours.

I've made a half dozen specialized chucks over the years and much prefer to start with a pre-machined backplate like that. It makes things a bit bigger than need be, but it's never been a problem.

If it turns out that you have the wrong backplate, keep me in mind. I'll happily give you fair change for it cuz I'm sure I'll have a use for it down the road.

For what it's worth, the only time I've ever turned one down or faced one is to true it up and/or machine mounting lips into it. The extra mass never hurts and as long as your spindle can handle it (and a D1-5 certainly can), it adds rigidity, rigidity, rigidity..... LOL!

 

[thestelster]

I had thought your lathe was D1-6 not 5. I'm a bit surprised at that. Mine is D1-5.

Accusize sells several different back plates. I believe the thick one like yours is steel and the thinner one is cast iron. I have at least one of each. I like the thicker steel one like yours.

I've made a half dozen specialized chucks over the years and much prefer to start with a pre-machined backplate like that. It makes things a bit bigger than need be, but it's never been a problem.

If it turns out that you have the wrong backplate, keep me in mind. I'll happily give you fair change for it cuz I'm sure I'll have a use for it down the road.

For what it's worth, the only time I've ever turned one down or faced one is to true it up and/or machine mounting lips into it. The extra mass never hurts and as long as your spindle can handle it (and a D1-5 certainly can), it adds rigidity, rigidity, rigidity..... LOL!

I definitely have D1-5.

If I face the backing plate down to Atlas dimension, 1.125", thick, I'll reduce the weight by around 4lbs, which is currently at 11.5lbs. So less strain on the spindle bearings as well.

But if I keep the plate full thickness, I could use it for future chucks.

Either way, going from a 14" Pratt Burnerd at 106lbs to a 6" at around 30lbs will be a great relief to both my lathe spindle, as well as my back and knees!

 

[Susquatch]

So less strain on the spindle bearings as well.

Maybe, but maybe a bigger flywheel REDUCES strain on the bearings by damping cutting loads - especially on interrupted cuts. I don't really know either way.

But if I keep the plate full thickness, I could use it for future chucks.

Well that's pretty much guaranteed given what you do for a living!

I suppose you could buy a thinner cast iron backplate and be done with it. They are significantly less money than the thick steel ones. That's what I would do in your shoes and mine too.

 

[Dabbler]

"... leave at least a 1/2" full diameter..."

sorry my weird way of talking... You were concerned about 1.8" thick - and I hypothesized that you might whittle it down to 1/2" thick. Both of my 8" chucks on my 12" lathe and my 10" chuck on my 14" lathe have 1/2" thickness at full diameter.

On the big lathe (D1-6) they are 3/4" thick at full diameter, but the boss for the set-tru extends about .600 more than that.

I don't see the need for more than about 1.5" [edit] for an reasonable purpose. The collet chucks I have can be mounted with 1.5" thickness (which is still pretty thick in my assessment).


... I mistakenly thought you were D1-6 as well - I assumed based on the size of your lathe.

 

[Susquatch]

I don't see the need for more than about 1/5" for an reasonable purpose.

Do you mean 1.5?

 

[thestelster]

sorry my weird way of talking... You were concerned about 1.8" thick - and I hypothesized that you might whittle it down to 1/2" thick. Both of my 8" chucks on my 12" lathe and my 10" chuck on my 14" lathe have 1/2" thickness at full diameter.

On the big lathe (D1-6) they are 3/4" thick at full diameter, but the boss for the set-tru extends about .600 more than that.

I don't see the need for more than about 1/5" for an reasonable purpose. The collet chucks I have can be mounted with 1.5" thickness (which is still pretty thick in my assessment).


... I mistakenly thought you were D1-6 as well - I assumed based on the size of your lathe.

Hi John, Ism talking about dimension B in the attached picture.

 

[thestelster]

Sorry, this is the correct specs for the type of chuck I want to get.

 

[Dabbler]

There doesn't seem to be much extra depth beyond the studs? My D1-6 studs have about .750 of thread, with about .300 of straight shank that needs accomodating, so at least 1.1" thick in this format??? Is the chuck you are buying a set-tru style?

 

[thestelster]

There doesn't seem to be much extra depth beyond the studs? My D1-6 studs have about .750 of thread, with about .300 of straight shank that needs accomodating, so at least 1.1" thick in this format??? Is the chuck you are buying a set-tru style?

Hi John, I plan on getting a 6"-4-jaw independent chuck.

As you can see on the attached photo, the depth that the camlock studs thread into the backplate is app. 1.040", so I think that a backplate thickness of 1.125", (not including the register thickness for the chuck recess), should be fine. That is the thickness of the Atlas "D1" backplates for chucks up to 10".

 

[thestelster]

So I decided to test fit the backplate to spindle nose. Well it appears there is app. 0.0003" radial play, which is probably acceptable since this will be for a 4-jaw independent chuck. But I decided to work the backplate a bit.

 

[Dabbler]

So it doesn't lock onto the spindle nose taper??? That is not good.

 

[thestelster]

First I indicated and zeroed a spot on the backplate to get an initial height. Then I used sheets of sandpaper on the surface plate, and using a figure eight motion with a flick of the wrist at the top to rotate the backplate slightly, started sanding away. 240 grit paper, 5 minutes with the right hand, then 5 minutes with the left. Cleaned and measured and used a new sheet. I don't know if this is best practice procedure, but I don't have a lapping plate.

 

[thestelster]

After about 10 sheets of sandpaper, I ended up removing about 0.0005" from the backplate. When I tested on the spindle nose there was zero lateral play and you could feel that the engagement was indexing on the tapered nose before the flat.

I put the camlock studs on, tightened everything up, then loosened them, and I needed to tap the backplate to loosen it off the nose. So all seems to be good so far.

 

[Susquatch]

When I tested on the spindle nose there was zero lateral play and you could feel that the engagement was indexing on the tapered nose before the flat.

I'm actually surprised that you encountered that. It has never happened to me yet and I have a good dozen different d1-5 attachments.

Kudos to you again Stell! Another scary job well done. There might be some who would say that wouldn't work, but I'm not one of them.

Knowing you, you will not forget to index the backplate now so it never goes home to the wrong bed.

 

[Dabbler]

I put the camlock studs on, tightened everything up, then loosened them, and I needed to tap the backplate to loosen it off the nose. So all seems to be good so far.

Very nicely done!

 

[Susquatch]

I put the camlock studs on, tightened everything up

Hey Stell, in your last photo, I noticed that your spindle cams are numbered. Is there a reason for that? Isn't a simple index mark adequate?

 

[thestelster]

Hey Stell, in your last photo, I noticed that your spindle cams are numbered. Is there a reason for that? Isn't a simple index mark adequate?

Aren't all D1 camlock noses numbered? That's how my lathe came. It looks factory stamped But it also helps me tighten them in an orderly fashion 1-4-2-5-3-6, repeat x 2 or 3.