9x20 chuck backplate

[savarin]

I am considering making a new backplate for a 5" 4 jaw chuck santa has ordered for me.
I have available some 2" round bar and 1" plate. (free, my price)
What I would like to know is if the following process would work and be strong enough.
Turn a 45 degree taper on the 2" bar, set the end of the taper onto the 1" plate, weld up to fill, set 1" plate on faceplate and bore the hole all the way through to size, cut the 39x4mm thread all the way, bore the register to size, remove from face plate and screw onto spindle (hoping it all fits) turn to size, face off both sides, turn to chuck register, drill fixing bolts for chuck.
I will have a test spindle to ensure the thread and register is correct.
A major question is - because I will be boring out after welding and cutting into the internal part of the weld will that bit of weld cut ok or will it be too hard?
If the latter can anyone suggest a suitable heat treatment to allow it to be threaded.
Thanks

 

[chuckorlando]

I have turned welds on my 9x with no problems at all. So long as the mating surface is cut after it has been mounted on the threads, I would think you would be just fine. Provided you can weld

 

[Bill Gruby]

I don't believe it will give you a problem Charles. Welds are lathe cut all the time. Just go easy and don't get anxious nearing the last cut and try to hog it all at once. Will you be using an insert?

"Billy G"

 

[savarin]

I have turned welds on my 9x with no problems at all. So long as the mating surface is cut after it has been mounted on the threads, I would think you would be just fine. Provided you can weld

welding not a problem, all processes, fully positional.
I suspect I will only use sticks for this one.

 

[savarin]

I don't believe it will give you a problem Charles. Welds are lathe cut all the time. Just go easy and don't get anxious nearing the last cut and try to hog it all at once. Will you be using an insert?

"Billy G"

HSS Bill, then I can take fine cuts. I dont really like inserts.
Nice to know its machinable. I'm hoping my calculations are correct and that the join will be just kissed when threaded so its all solid metal but only just into the thread. Dont know why I want that it just feels correct.

 

[Smithdoor]

I use cast iron weight set for my backing plate.
I have use steel plate both work good but since I no longer have plate around I use weight sets / Barbells and it is low cost as ever one will give up the weight.
If look close at the Avatar to left you will see a cast iron weight on the chuck

Dave

I am considering making a new backplate for a 5" 4 jaw chuck santa has ordered for me.
I have available some 2" round bar and 1" plate. (free, my price)
What I would like to know is if the following process would work and be strong enough.
Turn a 45 degree taper on the 2" bar, set the end of the taper onto the 1" plate, weld up to fill, set 1" plate on faceplate and bore the hole all the way through to size, cut the 39x4mm thread all the way, bore the register to size, remove from face plate and screw onto spindle (hoping it all fits) turn to size, face off both sides, turn to chuck register, drill fixing bolts for chuck.
I will have a test spindle to ensure the thread and register is correct.
A major question is - because I will be boring out after welding and cutting into the internal part of the weld will that bit of weld cut ok or will it be too hard?
If the latter can anyone suggest a suitable heat treatment to allow it to be threaded.
Thanks

 

[savarin]

I use cast iron weight set for my backing plate.
I have use steel plate both work good but since I no longer have plate around I use weight sets / Barbells and it is low cost as ever one will give up the weight.
If look close at the Avatar to left you will see a cast iron weight on the chuck

Dave

Hi Dave, how large is the hole in the centre of the weight and how wide are they?

 

[jumps4]

the welds can be hard but carbide cutters and going slow in the rough areas it can be done. my question is weather it should be stress relieved before machining so it stays stable and don't warp over time.
I made mine from a 6" backing plate from littlemachineshop.com that is $39.95 . cast iron, pre-machined to fit spindle, just turn diameter and shoulder for the chuck back, drill and bolt up.
http://littlemachineshop.com/products/product_view.php?ProductID=1922&category=
steve

 

[sk1nner]

I use cast iron weight set for my backing plate.
I have use steel plate both work good but since I no longer have plate around I use weight sets / Barbells and it is low cost as ever one will give up the weight.
If look close at the Avatar to left you will see a cast iron weight on the chuck

Dave

I've heard of others doing this. One questionI have is, alot of the people that have done this reported that the top layer on the weight was very nasty and dulled the cutting tool very fast. Did you experience this and if so how did you deal with it?

 

[Smithdoor]

It about 1" id I have found the width 1" to 1 1/2 some are small. Works great for 1 1/2 8 tpi spindle

Dave

Hi Dave, how large is the hole in the centre of the weight and how wide are they?