Squaring off with Lathe

[Quake]

Getting started on a bar stock hot air engine.

The kit has a piece of round bar stock that needs to be, among other things, turned in to a 40mm square block. I have a mini-mill and I realize that would be the easiest way to turn round bar into square bar, but what about using the 4-jaw chuck on my 10x22? I could mount the bar stock "side ways", ie, the flat ends of the stock against 2 of the jaws, and machine a side flat? Always used my mini-mill for such things, but I'm doing this project to learn some new skills - especially on the lathe.

What if I didn't have a mini-mill, what is the best way to turn round bar stock into square bar stock with a lathe?

-Quake

 

[Philjoe5]

Personally I don't have the skill to properly make a square block from a round on the lathe though I could imagine doing it in the fashion you suggest. I do know some folks who can do most every machining operation using only a lathe. As they say, "If all you have is a hammer, everything looks like a nail". :

If you figure it out or do it successfully let us know how you did it.

Cheers,
Phil

 

[shred]

4-Jaw and facing various sides flat is how you do it in the lathe.

 

[bearcar1]

Hi Quake, my thoughts are basically if you have the capabilities and know-how, to create a square block from a round (you have the mill and understand the steps required) why would you want to take the risk of possibly ruining a good piece for a build by doing so. If it is merely an apprentice exercise to gain the experience, use something that doesn't matter if it gets screwed up should that happen. To answer your question, the same basic procedure/steps that apply to performing this task in the mill would also be used if you did it on the lathe. Get two sides square to each other and work from there to create the cube. Begin by facing the ends and as you said mount it length wise in the 4 jaw and turn a flat the required size, turn the part over in the chuck so that the opposite side to the one just cut is exposed to the cutter and proceed to face cut that to the required width. Now you should have four of the six sides finished and they should be square to one another if the proper care in lining them up and seating them in the chuck was followed. Rotate the almost finished piece 90* so that one of the still round side projects towards the cutter and face cut it to size, and finally, turn the piece 180* and face the remaining round to final dimension. Again, this is the same basic procedures used if making a cube in a mill, only difference being is the use of a chuck instead of a vice and the attitude of the cutter being 90* from vertical. I do hope this makes sense, but mostly I would suggest doing one or two practices before attempting the process on a good 'finish' piece.

BC1
Jim

 

[Quake]

Thanks for the suggestions - figured that was the way to do it but thought I'd see what you all had to say. Just trying to "level up" my machining skills with this project and it's all bar stock and I have plenty (knock on wood) extra, so if I mess it up I can keep re-doing until I get it right.

I've met some guys that use lathes for lots of things I normally go to my mini-mill for and I'd just like to expand my skill set with the lathe - just upgraded from a 7x10 to a 10x22, so I suppose that has something to do with it too.

I'll get a build thread going before long so we'll see how this turns out.

 

[mcsqueezy]

its simple 4 jaw chuck as you said face of one side till its desired surface size, turn round pushing it on parallels to ensure its parallel to the face just cut and do it again, turn 90 degrees holding on the two flat faces face off then, turn over again and use parallels and then face of and then do the same the end of the 'round' bar thats no longer round and is square till it is the desired dimensions.

 

[kvom]

The side faces will be interrupted cuts, so depending on the size and material you may need to use a small DOC and multiple passes.

 

[Jasonb]

If you want a bit of practice then take it down to 42mm square on the lathe and if all is still going OK finish it on that, if not just take the last 1mm off all faces on the mill.

Lathe should be a lot quicker to remove the material.

J

 

[bazmak]

If you dont have a mill then it can be done in the lathe using a 4 jaw
A facing cut in the lathe is usually slightly concave causing problems
If you have a mill then that is the easiest and most accurate.No point in
doing the job the hard way unless you have to.Most jobs can be done
multiple ways,the skill is choosing the best way.Regards barry