# How To Approach This Job



## Transformer (Feb 3, 2016)

I have a simple job to do but very little machining experience.  I need to make some washers, 8 at 2" and 1/4 thick with a 7/16 hole  and 8 at 1.25" and 3/16 thick with a 3/8 hole.  I have a 1 ft piece of 2" hot rolled steel.  I have thought of 3 ways of doing this.

1.  Face off.  Drill an undersized hole.  Set up the tail stock. Part off the 1/4 thick pieces.  Drill to 7/16 on the drill press.  For the smaller washers then turn down to 1.25 diameter, part off the pieces and then drill to 3/8 on the drill press.  (Tail stock because I am not sure if the 3 jaw will hold the material well enough for parting off.)

2.  Cut 3" off the piece I have.  Face, drill to 7/16, part off the pieces.   Mount the remaining 9", drill to 3/8, turn down to 1.25 and part off the pieces.

3. Same as number 1. but do the 1.25 diameter pieces first.

Or ??????????  I would appreciate comments on what approach might be best, or how you would do it.

I have a 10" Grizzley lathe, converted to CNC.  I also just purchased an insert type parting tool.


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## Al 1 (Feb 3, 2016)

Drill on lathe before parting. Why try and set up on press?


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## Bill Gruby (Feb 3, 2016)

It is an all lathe operation as already said. Face the stock off. drill the hole on size, cut the OD to size and part them off. You never have to leave the lathe till they are done. Two machines is a waste of time IMHO.

 "Billy G"


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## Bob Korves (Feb 3, 2016)

First face off and drill a 3/8" hole in the work deep enough for the thickness of the 1-1/4" washers and the loss due to parting, turn down to 1-1/4", and then part them off.  It helps to chamfer each hole on the visible end before it it cut off, and chamfer both edges of the O.D. after parting it part way off.  When finished with the 1-1/4" washers, face off and drill to 7/16", turn or polish if desired on the O.D., and repeat the parting and chamfering until done.  One side of the I.D. will need to be chamfered or deburred manually.  Depending on desired finish, you may need to face each washer as you go.


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## epanzella (Feb 3, 2016)

Cutting off a 3 inch hunk is not enough because of the stock turned into chips by the parting tool. Add up the cuts and the washers and then leave at least an inch in the chuck for holding. A bit more if you parting tool won't work in close to the jaws. Turn the OD for the stack. Drill for the stack. Part off.


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## Transformer (Feb 3, 2016)

Thanks folks.  Do you think setting up the tailstock is necessary?


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## Bill Gruby (Feb 3, 2016)

You have to put the Drill Chuck someplace LOL No it's not necessary to set it up for anything but drilling.

 "Billy G"


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## brino (Feb 3, 2016)

Lots of good advice above, I only have one thing to add......

You mentioned twice about parting while using the tail-stock



Transformer said:


> 1. Face off. Drill an undersized hole. Set up the tail stock. Part off the 1/4 thick pieces. Drill to 7/16 on the drill press. For the smaller washers then turn down to 1.25 diameter, part off the pieces and then drill to 3/8 on the drill press. (Tail stock because I am not sure if the 3 jaw will hold the material well enough for parting off.)



That is a dangerous combination!!!
If the parted off piece has no where to go it will jam in the gap and at best stall the lathe and at worst be launched at your face. Please don't do that!
It is the equivalent of kick-back on the table saw.

One possibility if your setup is not rigid enough to part-off without tailstock support is to start parting with the tailstock, but STOP WELL SHORT of the internal hole ID. Then power off the lathe and finish with a hacksaw.



Transformer said:


> Do you think setting up the tailstock is necessary?


as above; only for holding the drill chuck!

Play Safe!
-brino

by the way there is a bunch of good suggestions for parting off here:
http://www.hobby-machinist.com/threads/parting-for-idiots.32938/
http://www.hobby-machinist.com/threads/parting-difficulty.35356/
it can be one of the tricky things to learn to do properly.


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## kingmt01 (Feb 8, 2016)

I try to stay away from a parting tool. However if I do use it I lightly support with a rolling center & before parting is complete I back it off a few tenths. 

Personally I'd part with a hacksaw & face one side of each washer then flip them all to face the last side.


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## Transformer (Feb 8, 2016)

Kingmto1: That is what I have been doing, face - hacksaw - repeat. 

The second side I have been milling.  Is there a way to hold the 1/4 thick pieces to face the other side in the lathe?  I still have more to do.  (And when I am done it will be parting off practice time.)


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## Uglydog (Feb 8, 2016)

If you are going to use the hacksaw over the bed, then consider putting some clean wood over the ways.
Just in case the saw slips....
Also, unplug the lathe or hit the disconnect, not just the switch.

Daryl
MN


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## brino (Feb 8, 2016)

Transformer said:


> Is there a way to hold the 1/4 thick pieces to face the other side in the lathe?



There are (at least) two lathe accessories commonly called a "spider".

One type (also called a "cat head") helps to hold odd shaped things and still centre them and turn them on the lathe like these:
http://www.hobby-machinist.com/threads/clever-things-we-do-in-our-shops.42684/#post-367464
http://www.angelfire.com/d20/lathework/page12.htm

The other type goes between the jaws of your 3 or 4-jaw chuck and helps to space things out from the face of the chuck like this:
http://neme-s.org/Spider.htm

These are just the first pictures of each type I found, various designs show up here regularly.

That second type could help you with facing the 1/4" thick washers. They do not allow much for the chuck to hold onto, so only light facing cuts are appropriate. I'd never use them for OD turning. That link for the second type also shows how you can use parallels instead.

-brino


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## epanzella (Feb 8, 2016)

Why all the hack sawing and facing? Maybe I missed something in this thread that makes that necessary but when I make washers or spacers I just face off the stock once to get started. I grind a little angle into my parting tool so that the loose piece falls off first and as the tool keeps going it faces the stock remaining in the chuck. Repeat as necessary.


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## sgisler (Feb 8, 2016)

Like so, only narrower:
	

		
			
		

		
	





Stan,
Sent from my iPhone using Tapatalk


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## epanzella (Feb 8, 2016)

sgisler said:


> Like so, only narrower:
> 
> 
> 
> ...


BINGO!


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## kingmt01 (Feb 9, 2016)

Great links Bruno.

I never said you have to hacksaw. I just said I hate using a parting tool & that's what I'd do instead.

I use parallels to hold my work at the correct spacing from the chuck.


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## brino (Feb 9, 2016)

epanzella said:


> Why all the hack sawing and facing? Maybe I missed something in this thread that makes that necessary but......



Yup you missed something. The OP stated that his current arrangement (his equipment, his experience, whatever) may not be up to heavy parting without using the tailstock for support. So we were trying to give an alternative.

However, I bet if he applied all the techniques linked to in post #8 above (locking the carriage, rigid tool, proper height, reduced spindle speed, etc.) he could learn to do the parting off operation safely and effectively. A great opportunity to extend his abilities!

-brino


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## kingmt01 (Feb 10, 2016)

I've never tried it but I've read s few members post that parting from the back side made things easier.


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## Paul in OKC (Feb 10, 2016)

I have parted things off with using the center in the end of the part many times. You do have to be careful. Be prepared, and stop the lathe as soon as it parts, then back the center up and remove the part. 
I would drill and turn to size. If doing this in cnc mode, you could program a little chamfer on both edges with the part off tool before cutting off.


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## kingmt01 (Feb 10, 2016)

Going along with what Paul said I've seen a YouTube where after the work was cut most of the way their they went to the innate to finish the part & left the work having from the tool.


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