# Backing plate for a jet 1236p chuck 60mmx8tpi



## Bill K (Jun 3, 2018)

Hello all,
I'm one of the frequent lurkers on the site, just getting started in some serious amateur machining work. Finally got around to buying me a lathe and a mill, and a whole bunch of tooling, I am a retired shipwright so I have some some experience in machining, but mostly in welding, mechanical assembly and dc electrical , among other stupid things I've done in the past .
I had a 1340 jet a while ago but found it too big for my shop so I got rid of it and got a 1236p jet lathe, along with a mayford ? knee mill, and I've got oodles of really nice tooling to go with them, ended up with a ALoris quick change head along with over 30 bit holders for it, I'm going to convert both of them to variable frequency drive or DC drive. I'm not sure witch yet along with digital readouts on both.
Anyway, the first thing I did was by a six jaw 8 inch Chuck for the lathe with a 2 1/4 by 8 tpi backing plate since I only had the Collett Chuck shown in the picture when I got the lathe, little did I know that the spindle on my lathe was a metric instead of American, I found out too late that it was a 60 mm x 8 TPI now I'm stuck since I don't have anything to turn out my own backing plate and I can't find anyplace to buy a backing plate in 60 mm, so my question is does anybody else have this lathe and if so, would they be willing to turn out a proper backing plate for my 8 inch Chuck? Of course any expenses including your labor and material will be covered along with shipping
the other option I was thinking of was that I could maybe grind my spindle down a little and succeed in doing it that way, I would end up having to remove some of the top thread dia. But it might just work, looking for opinions here.
Any help will be greatly appreciated. And of course if any parts are made monetary compensation will be made.
Thanks: zoomsplatt 
you can call me at 360-420-0296 or send me your contact information and I will call you. or email


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## Eddyde (Jun 4, 2018)

Grab this then you can make sa many as needed. I say grab because anything 60mm 8 TPI seems virtually nonexistent.
https://www.ebay.com/itm/Jet-8-4-Ja...825116?hash=item3f91aabb9c:g:90kAAOSwZvRaXPuw
No way would I try to regrinding the spindle.


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## craptain (Jun 4, 2018)

Absolutely do not grind the spindle. I am sure there's a few here that could help out, but in any case I would grab that chuck above. A 4 jaw is good to have around anyway. 

Sent from my SM-G930T using Tapatalk


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## Dave Paine (Jun 4, 2018)

For the present backing plate, do you have enough metal to bore this out and insert a bushing?

I had never heard of 60mm spindle thread so I just learned something.   I am surprised they went with metric diameter but imperial thread.

I have a Grizzly G9249 lathe, 12x37 which looks very similar to yours.  I am happy mine has normal 2 1/4in x 8 tpi thread.


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## akabud (Jun 4, 2018)

I have an extra backing plate I could part with. I have the same lathe as you and I just checked and it fit.


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## Bill K (Jul 26, 2018)

Eddyde said:


> Grab this then you can make sa many as needed. I say grab because anything 60mm 8 TPI seems virtually nonexistent.
> https://www.ebay.com/itm/Jet-8-4-Ja...825116?hash=item3f91aabb9c:g:90kAAOSwZvRaXPuw
> No way would I try to regrinding the spindle.


Hi Eddie
 sorry it took me so long to get back to you I've been away for a while down in Florida.
I ended up finding a machinist here in my area that bored out the throat on the backing plate and the 8 tpi threads actually fit! Go figure . So the problem is solved for now, still got a few other things to address on the lathe, like I found two striped gears , but I actually found a grizzly lathe, older one that matches up to my lathe so I ordered the gears ,hope they fit.


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## Bill K (Jul 26, 2018)

akabud said:


> I have an extra backing plate I could part with. I have the same lathe as you and I just checked and it fit.


Hi akabud
thanks for the reply, for now I've got the problem fixed, but having an extra backing plate might be a good idea, how much do you want for it?


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## Bill K (Jul 26, 2018)

Dave Paine said:


> For the present backing plate, do you have enough metal to bore this out and insert a bushing?
> 
> I had never heard of 60mm spindle thread so I just learned something.   I am surprised they went with metric diameter but imperial thread.
> 
> I have a Grizzly G9249 lathe, 12x37 which looks very similar to yours.  I am happy mine has normal 2 1/4in x 8 tpi thread.


Hello Dave.
Yeah these are pretty rare. Apparently ,of course I got a go and buy one .


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## Bill K (Jul 26, 2018)

Dave Paine said:


> For the present backing plate, do you have enough metal to bore this out and insert a bushing?
> 
> I had never heard of 60mm spindle thread so I just learned something.   I am surprised they went with metric diameter but imperial thread.
> 
> I have a Grizzly G9249 lathe, 12x37 which looks very similar to yours.  I am happy mine has normal 2 1/4in x 8 tpi thread.


Hello Dave.
Yeah these are pretty rare. Apparently ,


craptain said:


> Absolutely do not grind the spindle. I am sure there's a few here that could help out, but in any case I would grab that chuck above. A 4 jaw is good to have around anyway.
> 
> Sent from my SM-G930T using Tapatalk





craptain said:


> Absolutely do not grind the spindle. I am sure there's a few here that could help out, but in any case I would grab that chuck above. A 4 jaw is good to have around anyway.
> 
> Sent from my SM-G930T using Tapatalk


Hi craptain
while I was in Florida I managed to pick up at 8 inch 4 jaw that's like new. found it in a flea market over by Webster for $25!, Removable backing plate so I'll have to make another but I'm a happy camper.


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## Bill K (Jul 26, 2018)

Bill K said:


> Hello all,
> I'm one of the frequent lurkers on the site, just getting started in some serious amateur machining work. Finally got around to buying me a lathe and a mill, and a whole bunch of tooling, I am a retired shipwright so I have some some experience in machining, but mostly in welding, mechanical assembly and dc electrical , among other stupid things I've done in the past .
> I had a 1340 jet a while ago but found it too big for my shop so I got rid of it and got a 1236p jet lathe, along with a mayford ? knee mill, and I've got oodles of really nice tooling to go with them, ended up with a ALoris quick change head along with over 30 bit holders for it, I'm going to convert both of them to variable frequency drive or DC drive. I'm not sure witch yet along with digital readouts on both.
> Anyway, the first thing I did was by a six jaw 8 inch Chuck for the lathe with a 2 1/4 by 8 tpi backing plate since I only had the Collett Chuck shown in the picture when I got the lathe, little did I know that the spindle on my lathe was a metric instead of American, I found out too late that it was a 60 mm x 8 TPI now I'm stuck since I don't have anything to turn out my own backing plate and I can't find anyplace to buy a backing plate in 60 mm, so my question is does anybody else have this lathe and if so, would they be willing to turn out a proper backing plate for my 8 inch Chuck? Of course any expenses including your labor and material will be covered along with shipping
> ...


Thanks to everybody who reply to this, it wasn't as serious a problem as I thought, apparently the 8 TPI threads
are very close to American sizes as far as the diameter goes. The problem was in back of the threads the clear part was either 63 or 66 mm I can't remember now. So all we had to do was remove a little material from the 2 1/4 inch bore on the 2 1/4 inch by 8 TPI backing plate, so everything worked out well, while I was down in Florida I managed to pick up an almost new 8 inch 4 jaw Chuck, at a flea market for $25! It has a smallbore on the backing plate. I think 1 3/4" , which gives me plenty of material to open it up and put 8tpi threads so I should be all right there, next problem is the striped gears in the gearbox, but I think I've got that problem solved, grizzly had a lathe that matches up to this one that they made back in the 80s and they still have full parts for it. Where jet has nothing for this lathe anymore. . I guess I'll find out shortly as I ordered the gears. I hope they fit 
  after I get the gearbox and the cross carriage etc. cleaned up and adjusted I'm going to convert it to either variable frequency drive or DC with a pulse width modulator, I've got a 3 hp DC treadmill motor and the PWC's are readily available, I've also got a two speed three phase AC motor and a variable frequency drive controller for it in 2hp , I like the idea of the 3 hp DC because it's physically smaller and the way I want to mount it That will be important, I want to eliminate the counter shaft arrangement that comes on these belt drives and go directly to the spindle with a single belt, and the physical size of the DC motor makes that a lot easier.
  Anybody here use a treadmill motor with the PWC controller? Like to hear your opinions.
Thanks again


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