# Oxy/ac pattern torch



## Maddogmech1 (Oct 12, 2013)

While this isn't really a "machining" tool, it def has it's place in my home shop. I'm looking into building a pattern torch, basically a torch on a free swinging double jointed arm, with a finger that you can trace follow a pattern and it moves the torch to cut the shape out of whatever steel I'm using. Target project is qc plates for a kubota excavator to attach to the wood splitter I'm building for it. And a thousand other projects I'll come up with if I can make it work. Anyone have any good ideas or plans for one? For now I can run it manually, but eventually I'll motorize it


---------------------------------Why buy something when you can build it for twice the price!


----------



## hman (Oct 12, 2013)

When I read your description, I immediately thought of a pantograph.  Tried a web search for "pantograph torch," but all of those just looked like support arms, not pattern followers.  If you search on "pantograph" by itself, you'll get lots of what should be more useful hits. 

A pantograph is generally used to enlarge or reduce from an original, and that might not be what you want.  But if that's OK, do the search and pick up some design ideas.

A basic "how to" is available at http://www.peter.com.au/articles/pantograph.html 
If you replaced the flat bars with vertical plates hinged together, you could get a setup that also holds the torch upright.

Hope this is a useful start for you...


----------



## pineyfolks (Oct 12, 2013)

I think you are looking for a flame cutter http://www.youtube.com/watch?v=hdhEtUS_hew   Here's a better one http://www.youtube.com/watch?v=eolgB3r6Xq0


----------



## Uglydog (Oct 12, 2013)

I've got about an hour into looking for the cutting parallelgram plans I found last fall when I was looking for a straight line torch cutter. Please keep us posted as to how you fare! I'm also interested. 

Meanwhile check out: http://weldingweb.com/showthread.ph...tograph-shape-cutter-for-the-plasma-and-torch

Daryl
MN


----------



## Maddogmech1 (Oct 12, 2013)

I've looked into the pantograph vs flame cutter, and I think the cutter is more what I need. That pic of the blue one I think is perfect, just I may build a little bigger. The idea is cut the pattern from wood or sheet steel and then it's easy to reproduce in the 3/4" plate I need to build from and have them match perfectly. I will start this project next weekend and post updates as I go


---------------------------------Why buy something when you can build it for twice the price!


----------



## llarson (Oct 13, 2013)

Torch Mate used to make a small pantograph for using either a torch or plasma cutter. then quit. Demand was so high, they started selling the downloadable plans for $50. Good build of machine runs about $200. Look them up.


----------



## Tony Wells (Oct 14, 2013)

I have a project coming up that will be easier with a pantograph torch, and one I can borrow to do the job. It is motorized, with a knurled 1/4" diameter tracer driven around the perimeter of the pattern. I have used this one a couple of times, and like how it works. I cannot recall the make, but am planning on getting all the information to duplicate it. The "stylus" is actually magnetized and sticks to the pattern as it crawls it's way around it. Works great. Unless I am mistaken, the ratio is built in on this one to allow for the stylus size. You make the full size pattern out of thinner metal. I have used 10g for patterns when I used it. Last project was some large hex nuts. The across-flats was 6", and the thread was 2 3/4-8 I believe. Been quite a while. They are pretty handy.


----------



## Maddogmech1 (Oct 14, 2013)

Got a start on it last night, only a couple of hours, so I figured I'd tackle the torch holder first. I've tried to locate a machine torch for this project but they are pretty pricey so I'm using my cutting torch. So for I've got the holder and clamps done to hold the torch, and the plate it mounts to mostly machined out, with a curved slot so I can change the angle of the cut to do bevels if needed. Pics to come soon


---------------------------------Why buy something when you can build it for twice the price!


----------



## Uglydog (Oct 16, 2013)

I was rereading Guy Lautards 2nd Bedside Reader last night and noted that he had plans for a parallelogram engraver.
You might find that his plans are adaptable to a torch cutter.

http://lautard.com/books.htm

Daryl
MN


----------



## Maddogmech1 (Oct 16, 2013)

Thanks for the link. I've already started on the "design as I build" process though. I've got plenty of scrap around to build this, and I think I've settled on a single level arm. I sourced some bearings for the pivot points, so hopefully there won't be much flex. Has anyone ever heard of someone machining their own torch head? Or is this better left to the factories?


---------------------------------Why buy something when you can build it for twice the price!


----------



## Uglydog (Oct 16, 2013)

Maddogmech1 said:


> Thanks for the link. I've already started on the "design as I build" process though. I've got plenty of scrap around to build this, and I think I've settled on a single level arm. I sourced some bearings for the pivot points, so hopefully there won't be much flex. Has anyone ever heard of someone machining their own torch head? Or is this better left to the factories?
> 
> 
> ---------------------------------Why buy something when you can build it for twice the price!



Acetylene is volatile stuff! 
Perhaps you are are much better than I am. But, I wouldn't even, consider it. 

Daryl
MN


----------



## Maddogmech1 (Oct 26, 2013)

Here's some pics of progress on this project. 
	

		
			
		

		
	



This is the bearing housing I built from some DOM I had laying around. Bearings were around some I had, they came from some heavy duty industrial casters


This is the pivot arm. Just 2"x2" square thick wall I had


Lining up to check the fit. The shaft in the center I turned to 17mm and had to press it thru the bearings. 


Here is how the joint is assembled. The plates are welded to the left arm, the housing welded to the right arm. Center shaft is just tacked to the plates to retain it and ensure the shaft rotates in the bearing and not the plates. I've actually gotten the arm mounted to the backpost, but forgot to get pics of it tonight. Hopefully tomorrow I'll be tracing!


---------------------------------Why buy something when you can build it for twice the price!


----------



## Tony Wells (Oct 26, 2013)

Observation, for what it's worth. Normally you would wait until the welding was done and sometimes even stress relieved before boring for the bearings. Easier to get things lined up with the arms in this case, and less a problem with the bearing bores distorting.


----------



## Maddogmech1 (Oct 26, 2013)

Yes I know I've taken some shortcuts on this project in the name of saving time. In this case, I figured the sheer mass of the thicker steel and the fact it doesn't have to be surgical precision would allow for some slight distortion. My gamble paid off and the bores were fine after welding. The arm swings very smooth, so smooth in fact, that the bench it's mounted to isn't water level, and if I let go of the arm it will swing to the right on its own. 


---------------------------------Why buy something when you can build it for twice the price!


----------



## Tony Wells (Oct 26, 2013)

Oh, I wasn't being critical, just tossing out thoughts for others who may not be aware of the risks. Glad it worked out. Keep on updating us. 

On your question about building a machine torch head, there's no reason you couldn't, really. The tips themselves on the other hand are probably best bought. I would imagine though, that with a little patience you could turn one up a lot easier than building one. Maybe our least favorite auction site, or perhaps a visit to the LWS could pay off. A couple of them here do repairs on torches, and may get stuck holding a repair job and be willing to sell it to cover the repair cost. Worth checking, anyway. I'd do that before building one unless I really wanted something special that couldn't be reasonably bought.


----------



## Maddogmech1 (Oct 27, 2013)

Nothing special just a stubby machine torch. Found one on my local craigslust, for $250, titled "pipe beveling torch", must be a pipeliner. But I've already made the bracket for my hand torch so that'll be sufficient for now. If I get to where I use this thing often I'm sure I'll upgrade it eventually. Thanks for the ideas on where to check in the future though


---------------------------------Why buy something when you can build it for twice the price!


----------



## Maddogmech1 (Oct 27, 2013)

Some more eye candy. It works pretty well for being a quick and dirty project, and def needs more work, but it cut the plates I needed almost perfect. Only had to touch them up with the grinder a little and they both slipped right on the excavator


---------------------------------Why buy something when you can build it for twice the price!


----------

