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Making and using a hand crank lathe for use with a plasma cutter

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Picture of Making and using a hand crank lathe for use with a plasma cutter
. We make alot of stuff out of metal and a good circle was hard for me to do freehand. Using a tool like the one we show you here makes it easy to cut circles and washers out of any metal using a plasma cutter. It could also be used for some welding or grinding applications or as a crude PTO. For safety I designed this to be operated by 2 people .One person focuses on the feed speed (the turner),and the other focuses on the plasma gun location. This current design relies on having a hole in the center of the (to be ) circle. I usually have to have a hole there anyway but I plan to experiment with magnets to hold my rough blank in place.
 
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Step 1: Parts and pieces

You need to have a heavy base to keep the tool from walking or provide a way to clamp it down. I milled my base out of some old heavy pallet wood.

Step 2: Lay out the parts

To make this tool you will need a couple of pillow blocks. I had one that had been a disc sander in a previous life. You will also need a handle and some fasteners. To attach my circle blanks I have a shoulder bolt welded to the end of the shaft. This holds the blank flat so it don't wobble. The heat is far enough away from the wood to not be an issue and a piece of material will always be used as a hand rest and that piece will block the heat from the tool somewhat.

Step 3:

Attach the pillow blocks to the base using the shaft as a guide to centering and alignment. Attach a handle of some kind that spins as you turn it.This make it more comfortable than a solid handle. If your pillow blocks are not a snug fit for your shaft add some O rings. They can be gotten in any size from your plumbing store.

Step 4: The lathe

Step 5: How to use our hand crank lathe

Step 6: Making a circle and a washer

Phil B2 years ago
The shaft on your lathe appears to be too long for one person to hold the plasma cutter gun and turn crank, too. Do you use a helper or are you able to turn the crank and hold the gun, yourself?

Thank you for your Instructable.
drewgrey (author)  Phil B2 years ago
I opted for a 2 person tool because one person can focus on feed speed and the other can focus entirely on gun position. The same design could be scaled for 1 person operation though. Thanks,Drew
pfred2 drewgrey2 years ago
Come on, put foot pedals on it. You can do it! Steal a bicycle.
drewgrey (author)  pfred22 years ago
Actually a slow constant speed is what I need even for thin material. If I cut 1/2" or more the rotation speed will be a crawl compared to the cut I made in the video. What inspired me to make this was an early attempt to make a circle by chucking up a piece of steel on a stick in a big drill motor. DON'T do this! It does work but when the trigger is touchy and the thing speeds up suddenly while I was cutting the hot liquid metal spun from the disk like a pinwheel and rained down ..................Is that hair burning?
pfred2 drewgrey2 years ago
Maybe the dog's. When I cut and weld I wear protection.
drewgrey (author)  pfred22 years ago
I do also but I did not have my hat on under my helmet. I have thought of attaching one of my hats to the helmet . There was no damage but the kind of reminder that warns you and then makes you laugh...best kind.
pfred2 drewgrey2 years ago
I hate back lighting in my mask when I weld so I put a spare bib off a summer welding jacket over the top of my helmet. What I look like when I do that would probably make someone laugh, but I'd rather see what I was doing better.
If I may suggest an improvement;
Attach a rope and weight, run it around the axle and gravity should spin the lathe nicely.
You shouldn't be holding the torch. You should build a rig with the bicycle gears that not only engaged the wheel, but also activates the plasma burn. Good stuff though.;)
Robot Lover2 years ago
Very cool. If you added a tool rest you could get better circles. Good instructable!
drewgrey (author)  Robot Lover2 years ago
That is indeed in the future . I also want to create indexing holes for the nozzle of the gun so I can repeat exact sizes and step up in even increments. Thanks for the comment,Drew