Todays project a pantograph shape cutter for the plasma and torch

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I've got a job coming up where I need to plasma cut a bunch of holes 4" and smaller in 1/4" plate. My circle cutter for my plasma works fine down to about 4" but below that it becomes difficult to use. I've wanted a better way than just making a template for the hole. My experience is that the template gets dirty and slag blown on it to the point where it's difficult to slide the plasma torch and get a smooth cut.  Anyway I've been wanting a small portable shape cutter/pantograph for this job for a while. I don't want it to big. Commercial ones are big bucks if you can even find one as small as I want so I've been mulling this over in the back of my mind for a long time. It's been a little closer to the front since I've been getting these jobs with all the holes. Today the weather was bad enough that I didn't want to do the projects that I have waiting so I decided to get a start on it. Keep in mind that it was nearly 11:00am before I really got a chance to start and most of this was designed on the fly in my head as I was doing it using my mantra KISBF (keep it simple but functional). Somethings could be improved but overall I'm fairly happy with the way it's going so far.  The first pic shows how I got the hinges on the arm straight with each other. This is critical on a shape cutter since any angle here will make for a oval hole. I debated making it adjustable but really didn't see a easy way to do that with the time I have available. Thus I worked pretty hard getting them as straight as I could.  The other two pics shows my progress so far. Attached ImagesMillermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:That's my intention just didn't make it there today. I plan to trying to make it versatile so that I can modify later for such things as pattern cutting. Wish I had room for a CNC table. It would make some jobs easier. But I don't do enough of those type jobs to justify the expense much less the building space for one. That's why I wanted this one portable because I need to be able to store it out of the way when not in use.Millermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:Funny I have been thinking about one of these for the last couple of days, I need set on up for myself. I need a bit bigger though. Are you going to use a magnet for the tracing point? If so what kind.
Reply:Originally Posted by Mick120I was using a pantograph OA profile cutter back in '74 when I was manufacturing forklift chassis.It had an electro magnetic drive wheel that used to attach to the template hanging from an overhead frame and drive around the shape.Worked really well.Have to say I'm bloody spoilt having a 5' X 10' CNC table now tho.....best thing since sliced bread I reckon.
Reply:If most of what you do is cut circles.  Make a round flat plate with a series of holes in it that turns with a small crank and use it for your patern on top.  then you just put the follow pin in a hole of watever radii you want and turn the crank. Perfect hole every time.
Reply:very clever,
Reply:Originally Posted by Happy Bobwtf??
Reply:right, because the spam link is in the quote, so we need to do a second delete, and take care not to ban in that case.  Just report and be done with it.
Reply:Originally Posted by Tool MakerIf most of what you do is cut circles.  Make a round flat plate with a series of holes in it that turns with a small crank and use it for your patern on top.  then you just put the follow pin in a hole of watever radii you want and turn the crank. Perfect hole every time.
Reply:more, keep us posted I like the use of the PTO shaft.Millermatic 251Century 180 migSpectrum 625 Syncrowave 250DX
Reply:Originally Posted by CarterKraftmore, keep us posted I like the use of the PTO shaft.
Reply:The torch guide doesn't have to follow a true complete circle, it just needs to be guided in a 360 degree arc that shares its radius center point with the circle to be cut. Why not use a torch holding guide-arm that swings on an anchor that's centered above the cut? That is, an arm that's easily centered in common with a soon-to-be-cut  circle and can turn 360 degrees. A guide-arm having torch radius adjustments that are set with something like threads, a slot, or a gear rack, could be fine adjusted for an infinite number of cut diameters.Of course all this stuff and height adjustment too would be simpler to negotiate with a machine torchGood LuckLast edited by denrep; 12-21-2011 at 10:58 PM.
Reply:Originally Posted by denrepThe torch guide doesn't have to follow a true complete circle, it just needs to be guided in a 360 degree arc that shares its radius center point with the circle to be cut. Why not use a torch holding guide-arm that swings on an anchor that's centered above the cut? That is, an arm that's easily centered in common with a soon-to-be-cut  circle and can turn 360 degrees. A guide-arm having torch radius adjustments that are set with something like threads, a slot, or a gear rack, could be fine adjusted for an infinite number of cut diameters.Of course all this stuff and height adjustment too would be simpler to negotiate with a machine torchGood Luck
Reply:Originally Posted by irish fixitThat's the original plan and still might happen. That problem with the adjustable rod type is getting it set to exactly the right size. Even with a well made and marked rod. The circle attachment we had at my former employers had a really nice well marked rod but setting it to get the size you wanted required practice and luck. If I go that way I want some way of having a adjustment to calibrate the markings so that when you set on the mark you get what it says and not have to tweak it 1/32" one way or another from the mark.
Reply:I just passed on a broken arm pantograph for $150.    live and learnVantage 500's LN-25's, VI-400's, cobramatics, Miller migs, synch 350 LX, Powcon inverters, XMT's, 250 Ton Acurrpress 12' brake, 1/4" 10' Atlantic shear,Koikie plasma table W/ esab plasmas. marvel & hyd-mech saws, pirrana & metal muncher punches.
Reply:Originally Posted by denrepIt just takes a minute to dial-in on a piece of scrap. Adjust close and then  take just two small nips, 180 degrees apart, to know exactly what the final cut's diameter will be, kerf issues and all.  Then measure the trial piece's diameter and adjust the torch radius one half of  any distance that the diameter is off, to get a final cut setting that's right on the money, with just one measurement and one adjustment.Good Luck
Reply:Hi Here is a pantograph I built some time ago and have used it many times.[ame]http://www.youtube.com/watch?v=hdhEtUS_hew[/ame]   I have an PDF file I can send to thoses whom may want it just email me at [email protected]  its about 5 megs so I cannot attach it here.It is an OA torch now fout can be converted to plasma.I took the arm off and have been using it as a hot wire cutter for cutting foam to cast aluminum parts.  Merry Christmas to allTom Attached Images
Reply:Originally Posted by irish fixitTakes more than a minute. First you've got to find the scrap what's scrap anyway everything has a use.  Seriously I've been there and with a torch using different sized tips there's no help for it but with the plasma it's pretty fixed on kerf size so I'm hoping to calibrate it to the point where I don't need to do the test cut thing. . . .
Reply:I see what you're saying. I agree it's not the best solution overall but it's the best solution I can afford and have room for right now. I know perfect accuracy is not really that attainable but I'm looking for better than I'm getting right now. The truth is the project I'm doing accuracy isn't needed but rather smooth clean cuts are needed so that I can keep the cleanup to a minimum. It's the type of project where speed is needed to make it profitable and I hate to turn out work that doesn't look good. Even if the customer doesn't care.   I've been doing this with my circle cutter and a hole template. The circle cutter part is livable but the template part I'm not happy with. Plus I think this would be handy for some things I do on occasion.   I've considered several options for this and I'd love to have just a simple spin around circle cutter instead of the complex pantograph arms but spinning the heavy plasma lead around in a quick fashion really isn't doable. A machine torch would be to expensive no more than I would use it and making a swivel for plasma is way too complicated (I'd pretty much have to make the head as well).   I could easily do these cleaner with a torch but that would slow things down to much.Millermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:Originally Posted by acourtjesterHi Here is a pantograph I built some time ago and have used it many times.   I have an PDF file I can send to thoses whom may want it just email me at [email protected]  its about 5 megs so I cannot attach it here.It is an OA torch now fout can be converted to plasma.I took the arm off and have been using it as a hot wire cutter for cutting foam to cast aluminum parts.  Merry Christmas to allTom
Reply:Originally Posted by acourtjesterI took the arm off and have been using it as a hot wire cutter for cutting foam to cast aluminum parts.
Reply:Originally Posted by irish fixit. . .  I've considered several options for this and I'd love to have just a simple spin around circle cutter instead of the complex pantograph arms but spinning the heavy plasma lead around in a quick fashion really isn't doable. A machine torch would be to expensive no more than I would use it and making a swivel for plasma is way too complicated (I'd pretty much have to make the head as well).
Reply:Yeah I'm still working on the torch holder that's just the first part. I've run into a snag of it hitting the support arms when down low enough to work. I've got a couple of options but not the right stock for my favorite one. Hmm. Just remembered where some stock like I want is.  I'd like it to sit kinda parallel with the arm when in use. I'll make something to support the handle and work the trigger. I'd like to have a rack and pinion height adjustment but that gets to complicated and time consuming for this build. Thus the rather kludged setup I've made. At least it's easily changed out and is adjustable for square. This is one of my quick builds that may or may not get improved in the future. I'm trying to make it easily adjustable and easy to modify.   Hopefully I'll get a chance to work on it a little tomorrow. At least we got the rush job out today that I've been working on for the last 3 days.   Here's pics of the rush job I had to do this week. He blew up the engine in his other truck that I mounted this bed on last. Went to trade and got turned down on trading for another dodge so ended up with a chevy. Made my job much harder. Had to completely redo mounts, move fenders, etc. But we kicked it out in 2 1/2 days. His old backup truck got loaned out and the engine blown up on it so he was without truck making this a critical job for him. Attached ImagesMillermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:Wow, you've got a lot of irons in the fire. Nice job on the bed.--------For the circle cutter to use a tough-to-negotiate hand torch, without winding up its hose and having its handle sweep over the table, maybe it'd be possible to have a bearing mount around the nozzle? With the nozzle centered in a bearing the torch and hose could orbit around the cut, while "walking" within the bearing and thus not rotating with the cutting guide. Does that explanation make sense? Good LuckLast edited by denrep; 12-24-2011 at 01:08 AM.
Reply:Hi DSWLost foam casting has been used with great results.  The foam is covered with drywall cement before casting and covered with dry sand to support the casting aluminum.Here is a linear bearing assembly I cast and machined for a CNC table I am building.have funTom Attached ImagesOriginally Posted by denrepWow, you've got a lot of irons in the fire. Nice job on the bed.--------For the circle cutter to use a tough-to-negotiate hand torch, without winding up its hose and having its handle sweep over the table, maybe it'd be possible to have a bearing mount around the nozzle? With the nozzle centered in a bearing the torch and hose could orbit around the cut, while "walking" within the bearing and thus not rotating with the cutting guide. Does that explanation make sense? Good Luck
Reply:Originally Posted by irish fixit. . .  I've given some thought to finding a bearing that would fit around the plasma nozzle so that I wouldn't have the drag problem. It would make the template rather large since for the bearing to survive I think it would need to fit up away from the cut making the hole in the bearing slightly over 1". Lets see a quick check of McMaster shows a 1" hole sealed bearing to have a 2" OD. That would make the template about 1 7/8" larger than the hole needed. . .
Reply:Jeez Irish, maybe in my next life I'll come work for you for free just to learn. Foam cutter it brilliant from my shoes. You could do a little commune like the aluminum sail boat farm folks! 200amp Air Liquide MIG, Hypertherm Plasma, Harris torches, Optrel helmet, Makita angle grinders, Pre-China Delta chop saw and belt sander, Miller leathers, shop made jigs etc, North- welders backpack.
Reply:Originally Posted by denrepTo be more clear on my suggestion, the bearing doesn't have to be over the nozzle, (although in some ways that would be quick and simple)  the bearing just has to share its center with the nozzle's center. So for the same centering result as a "nozzle bearing" you could build a bracket that clamps to the torch body and holds an arbor centered above the nozzle. For circle cutting the "high mount" arbor would then insert into the guide-arm mounted bearing, located above the torch. Maybe the arbor would be held in the bearing by a collet and set screw? The arbor and bearing could be rather small and would be away from the cut's heat and not block vision at the line-of-cut, while still accurately centering the torch for its smooth guiding around a circle. Meanwhile, when not cutting circles, the handle would be easily freed, and useable for most cuts without removing the top-mounted circle guide arbor.Forget McMaster on this one, I'm talking about a fast-and-dirty build, right out of the junk drawer. A slotted arm that's somehow powered to slowly rotate. Maybe via variable speed electric drill? A bearing mount/torch carrier that slides in the the slotted arm and can be locked to set the cut's radius. An arbor on the torch that plugs into the bearing. That's it. Maybe a retired drill press, hanging from a bridge? The hanging drill press would give an instant precision height control and easily adjusted speed, and  clearance for large work.Good Luck
Reply:Originally Posted by Mick120Hey Denrep,I don't know what sort of plasma you're operating to have that many problems . . .
Reply:I have to agree with both in this case. I've used the old plasma's and know where Denrep's coming from. I've also seen my Hypertherm T-80 torch cut at a slight angle as well but I must admit that it's usually time to change consumables when it's doing that. The taper of the cut on thicker steel is one of the reasons I don't normally used plasma on thicker stock. It's pretty much impossible to completely eliminate it though I must admit that it's greatly reduced on my Hypertherm.Millermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:Nice looking cuts for sure. I'm sure the main reason for my taper is that I'm usually going as fast as I can go since I'm doing it by hand. I do know the old Lincoln plasma we had at my former employers definitely made a tapered kerf but I always considered it a kind of dinosaur even when it was new. They liked it because it was simple and powerful but it nearly put me off plasma cutters altogether. I used it on a track torch and pattern cutter a fair amount and no matter what you did you had a really heavy slag stuck hard to the bottom of any mild steel you cut.   I've been super happy with everything about my Powermax 1250. Ironically the only thing I wish for is the one thing I hated about every other plasma cutter before. I always wanted a 90deg torch for them for free hand. But now that I have one there's a lot of times when I wish it was a 75deg like the others had. Circle cutting is a prime example. My main problems with my circle cutter is the fact that my finger on the trigger won't clear the bar.Millermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:Originally Posted by Mick120Hey Irish,I've been thinking about what you're doing and, I reckon if you can go the extra mile, you really need to consider a small CNC plasma table.I've seen some of the work you've achieved and, believe me when I say, a LOT of the work can be done quicker and easier with the aid of CNC.I use my table all the time as a time saver....brackets, plates, all sorts of shapes and sizes can be made in minutes and, if you get a lot of circles as you sound like getting, they're a snap to do, accurately and repeatably.You don't need to spend a bundle either, I've seen a lot of good deals going on ebay etc, turn key operations, going for a fraction of new prices.Once you've had one for any length of time, you'll wonder how you ever did without one for so long.Do yourself a favour and, at least give it some thought.
Reply:Originally Posted by Mick120Damn....it doesn't rain....it pours.Sorry to hear about your situation mate, guess I missed the mark a bit there.I have seen the shop and, completely understand where you're coming from.It can get bloody hard to make changes when things like that happen in your life.....believe me when I say, I really feel for you.Must be nice to be getting some good paying work in tho.....that helps a lot.
Reply:Ok Ok. You convinced me.    Actually I already ordered it before you got this post up. I started to get a 15 deg as well but when added on top of a consumable kit and deluxe circle cutter kit it took it higher than I was comfortable with at the moment.  I actually looked to see if I could find any of the deals where you got the second torch with a new 85 but didn't find any. I could actually spring for that if I worked the money right but didn't find any with the extra torch. My 1250 doesn't owe me a dime. It's been great for about 8 years now. I do need to replace the pressure regulator on it since sometimes it likes to leak. But I've got a pressure regulator as well as a filter dryer, then motor guard filter on the cart itself before going into the filter dryer on the back of the machine so for the time being I've just lowered the pressure on the cart regulator.Millermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:Originally Posted by Mick120Think I might have to hit Hypertherm up for a spotters fee.....I'll be real interested to see your thoughts on the new setup.
Reply:Perfect!All three sides of the magic triangle are complete:Good enoughFast enough Cheap enoughGood Luck
Reply:Irish,Sometimes I brain fart, where is the pattern portion of this? Am I not seeing it or is it not in the pictures. I am finishing up projects right now and one of these in on my list.I have been following this daily, but I didn't have anything constructive to comment on and I need to finish up some stuff before I could even think about starting something else.A friend of mine is a gunsmith and he has a pantograph engraver and I was over at his place and spent about a hour looking it over and taking notes.I want a motor and I want to be able to adjust the multiplication factor, accurately I haven't decided but an adjustable 1-10 would be perfect. So a 2" piece of DOM tube would give me 2 to 20 inch circle.I have scoured the internet and really haven't seen the math to lay this out right, I know its geometry if I can't find it I am going to sit down and do it the hard way.Neat project !!!!!!
Reply:Yep it works. I still like your idea as well and might work on it sometime if I get a chance. But I already had this started and wanted to get it working before I started another project.   Thanks.Millermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:Where is your pattern part?
Reply:Originally Posted by fredschromIrish,Sometimes I brain fart, where is the pattern portion of this? Am I not seeing it or is it not in the pictures. I am finishing up projects right now and one of these in on my list.I have been following this daily, but I didn't have anything constructive to comment on and I need to finish up some stuff before I could even think about starting something else.A friend of mine is a gunsmith and he has a pantograph engraver and I was over at his place and spent about a hour looking it over and taking notes.I want a motor and I want to be able to adjust the multiplication factor, accurately I haven't decided but an adjustable 1-10 would be perfect. So a 2" piece of DOM tube would give me 2 to 20 inch circle.I have scoured the internet and really haven't seen the math to lay this out right, I know its geometry if I can't find it I am going to sit down and do it the hard way.Neat project !!!!!!
Reply:Did a little refining today. I redid the circle bar so that I could graduate it and make it so that it's possible to cut a smaller circle. The way I had it originally I could only go down to about a 2 3/4" hole. Now I can go down to about a 1/4" hole.   I also put bushing in the pivot at the top to get rid of the slight slack I had there to make a little more accurate. The holes still aren't perfectly round but they're with about 0.040" at the top and about 0.070" out at the bottom so not to bad overall. I think I can improve that with some tweaking of my stylus up top and some other adjustments.   Here's a short vid of it in use.[ame]http://www.youtube.com/watch?v=Ma3iH6CbPcA[/ame] and here's a couple of pics of the new mods. Attached ImagesMillermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:Here's a couple of video's of me making the parts I built this pattern / circle cutter for.   Here I'm making the fish plates, doublers, or bases for the lift eye's. These go on the clamp under the lift eye's to spread the load on the rings.[ame]http://www.youtube.com/watch?v=wrYgnZDWw6Q[/ame]  Here I'm making the lift eye's that get welded to the sides of the rings so that they can position the poles with comealongs.[ame]http://www.youtube.com/watch?v=BND_UJ8dZM8[/ame]Millermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:Brilliant.... and yet another tool I need to make.Lincoln pro mig 180Lincoln Square Wave Tig 300/wp 20/home built water cooler Victor, Purox, Harris, O/A welding/cutting setupsVintage Craftsman drill pressVintage Craftsman/Atlas 12"x 36'' lathe7''x 12'' w/c band saw Everlast 140 st
Reply:Thanks. Careful or all you ever do is make tools. It's a addiction take it from me. Millermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:Pretty cool Irish. Just an idea here, on your circle size bar you should put a couple of collars on it or stops, a simple small hose clamp would work, then you just slide to stop and cut. It looks like it is plenty fast as. Good jobMillermatic 252Lincoln 175 plusTA 185tswTA 161stlhypertherm pmax 45Victor torchHenrob torchAn S10 for each day of the week
Reply:Thanks. I considered stops but never got around to making them. If I was doing more of them they would of been nicer but just for 30 I made do with the markings pretty well.Millermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:I had a swamp cooler blowing on me from behind (have one aimed in the back door all the time for summer). It helped though it didn't get it all. I prefer to do plasma outside but the weather really wasn't good enough for it.   Thanks. It was a definite improvement over my old method. Lot's easier, faster, and cleaner cuts to boot. Much less cleanup needed. Just finished up the whole lot of them a few minutes ago. Ready to be picked up.Millermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:I've always wanted to add a extractor to the shop for the winter time work like this. I've got most of the stuff besides the ducting to make one just never had the time. In the summer it's not a problem since there's 4 swamp coolers blowing air through the shop out the door.   Yep. It's nice little time saver for this job for sure. I still need to fine tune it a bit more for rounder circles and I still want to rig it up for pattern following as well. We'll see if either ever happens. Millermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:Irish,Way neat I want to put one together but I need to cut a good straight line first, which is my current project, then I can work on pattern cutting.I did do a bunch of homework and math and think I have this figured out. But its parked for the moment. I haven't forgotten my multipler rule either.I wish there were 10 days in the week and 30 hours a day, sometimes I have more projects than one of Santas helpers right now.