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Building a tracing machine 2 projects

I was posting here a while back for info on tracers and pantagraphs. which leads to wondering about just building something. What I am trying to do is stack 6 .050 thick brass blanks and at least do alot of the roughing to match some patterns we have to duplicate. Most have many tight curves and I usually have to lay a piece out bandsaw as close as I can and then die file. some of these are alot of work and not cost efficient. These are patchboxes, toeplates and sideplate for muzzleloaders if ya know what that is. If I could mill out 75 % and then go in with saw to get sharp corners and also have less die filing it would save me ALOT of work. Waterjets, wire EDM, all that fancy stuff is too expensive. Its either some cheap system or doing it the same way as before I wondered if I could make a system using something like Thomson bearings in the x and y axis with my pattern at say 6 in from my clamped blanks. And also at 6 in a bearing same dia as cutter as my guide. I'm wondering about all the vibration and bouncing this is going to cause at the cutter and how to dampen this. I'm still going to be die filing a bit all over the parts but the smooter the finish the easier all round.

The second project is cutting info wood using a router as cutter. We have patterns and are trying to cut channels for muzzleloader rifle barrels. Were trying to duplicate some old guns so there are several different shapes to do. Plan so far is to use Thompson bearings and run the axis on a tube frame. the y axis runs on the x axis and at the center is a pivot blank to the left and pattern to the right. Anybody see any problems with this? I've used thompson shafting before but we used it just for moving large objects on frames we build on dip molding machines. I'm just a lowly machinist and find myself for the first time with out some know it all engineer telling me to do everything and somehow I'm now the shop know it all --- God help us

Reply to
ken
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It sounds to me like you need to build a CNC machine. If you're gonna go to the expense of buying Thomson linear shafting the maybe buying lead screws and servos won't be a bad idea. If you go with the shafting consider your load. It may be better to use the Frelon lined linear bearings than the ball bearings. The plastic lined bearing will damp out vibrations better which translates to longer cutter life and better finishes. So, see below for a method of building that may work for you.

1) Look for surplus linear motion components. There are lots on the market and much cheaper than new. Just google for these. 2) Use servo motors instead of steppers. 3) Buy, for $114.00 each the servo drives from Gecko. These will drive a motor at 80 volts and 15 amps. That's 1200 watts. Enough to drive a big servo motor. 4) Buy, for $250.00, the digitizing and motion software, along with the probe, from MAXNC. The stepper output software is much cheaper than servo output software. The Gecko drivers take step and direction input and convert it to servo output. 5) Buy, for about $35.00, from U S Digital, encoders for each axis.

You can also buy just the motion software from MAXNC. It is lots cheaper. There are also free stepper output programs available. Once again, Google is your friend. Get the software that uses G code. If you shop right you can build a machine for less than $2000.00 that will do what you want and more. If you want to make a pantograph with linear motion components then look at Guy Lautard's web site. One of his books has plans for a pantograph that could be scaled up to do larger parts. I wouldn't bother. Maybe you can buy a cheap import mill used and just hang the servo stuff on it. That could be still be done for $2000.00 and all the heavy work will be done for you. If you buy all the stuff new then you will probably spend more money than what a new machine costs. ERS

Reply to
Eric R Snow

There are at least 4 different gunstock duplicators on the commercial market. Google for "gunstock duplicators" and you can get some ideas for constructing your own. No sense in trying to reinvent a device that's been around for many years.

Randy

Reply to
Randal O'Brian

For doing all of the little metal pieces, a pantograph mill is quite versatile. Make a large pattern (5-10x the part size depending upon how big you want to work with and how big the mill is) by cutting a step in a sheet of plastic (or cut out a piece of plastic in the shape and glue to another piece) and you then trace around the pattern and cut the metal with the cutter in short order. Use the right size stylus (x times the size of the cutter) and you will faithfully duplicate the part to the size of the cutter for radiuses. You can also use the pantograph to mill out the holes in the wood for the metal pieces to a very high accuracy, even to the point where you can just press the parts into the wood and they'll stay until you pry them out.

-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works every time it is tried!

Reply to
Bob May

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