Stock Duplicator Build

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SouthPaw700

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Well I did some research on stock duplicators and came up with some general conclusions. Either they are too poorly built for regular use, or they are very expensive. So I decided I would build one myself. I'm going to go with a sort of gemini style duplicator. I got the first of the parts in today. Some 30mm linear bearings for the router/feeler arms to pivot/slide on.

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Infact if there was enough interest, and if we could get a really good design worked out we could get some of the parts lazer cut for a group build. Cuts down on the labour, and makes for righteous parts.
 
double gun said:
Infact if there was enough interest, and if we could get a really good design worked out we could get some of the parts lazer cut for a group build. Cuts down on the labour, and makes for righteous parts.
Click to expand...

Yeah if we can get all the kinks worked out and come up with something useful, that might not be a bad idea.
 
How many axes of movement will you have?
I've used an industrial 12 spindle Northstar machine for stock carving. The pattern and work could be rotated, and the stylus and cutters would move foreward and back, up and down, and left and right.
One US carver made a machine that added rotation of the stylus and cutters, as well as rocking fore and aft. Five axis movement for the cutters.
What sort of powerhead are you using? Many routers are pretty big and bulky to mount at the end of the arm. The Northstar had six motors mounted back on the carriage, each motor driving two spindles via flat belts. It was a very loud, rather intimidating machine to use.
Vibration of the wood can be an issue. Longer stocks can be a challenge. The closer the workpiece is cut to shape before starting to carve, the better.
What cutters will you use?
 
Mine will move left to right, front to back and up and down. The stocks will be bolted to an assembly that rotors with cogs that are linked with a chain so that they both turn the same amount at the same time. The plan right now it to make a round collar to attach the router to the end of the cutting arm. This arm will have a weigh at the other end of it for counter-balance so that the arm assembly can easily be moved up and down with very little effort.

I will likely cut the blanks out on the bandsaw as close as I can before putting it in the duplicator, there by eliminating a lot of the work for the router.
 
Most router bits are pretty short. Given the large diameter of many routers, it can be tricky to get to the workpiece. I don't know if longer shank bits are available, these would give a bit more reach. Its not so much the weight of the router, it is the bulk of the powerhead. Maybe there are routers that are smaller in diameter, yet powerful enough.
Stylus heads can be turned to match each cutter; make them slightly larger than the actual cutter. Different cutters may be used for roughing out, finishing, inletting.
Regular router bits aren't intended for 3D carving, perhaps there are others better suited. You want bits that will cut with minimal vibration and chatter. Maybe carving machine manufacturers sell them.
Steel link chain, or a timing type belt could be used to rotate the pattern and workpiece in sync. You will need a system that will hold both in place until deliberately turned.
 
Router bit availability has changed a lot recently, due to CNC Signmaking routers, as much as anything. Worth looking at the signmaking bits maybe.

One of the guys on, IIRC, the Accurate Reloading Gunsmithing forum sells a thumb drive with his design on it. Lots of experience there that you don't have to learn first-hand, if you go to the bother of tracking him down.

Cheers
Trev
 
long bits

An extension can be easily made on the metal lathe. I made up 2 inch and 3 inch long extensions for my router. In most cases, the 2 inch one gives the room you need. A 1/2 inch CRS rod can be drilled for the cutter bit, and a set screw used to lock the bit in place. If you use a 1/4 inch router, simply turn a 1/4 inch shank on the piece. A 1/2 inch diameter is all right in most cases, because you are hogging off excess wood. You might need a special bit for finer work, but 95% of the work can be done with this set-up.
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Still getting parts at this point. I got my 3ft of 30mm bearing rod on friday. This is the rod the linear bearings will ride on and allow the feeler and router arms to move up and down and side to side. I'm trying to decide what I want to use for rails now. Gemini just uses 2" steel tube and uses spindle rollers. This might be ok, but seems like it could be a little sloppy. I'm toying with the idea of getting 1" supported linear bearing rail, and open block linear bearings. This would be quite strong and quite precise.
 
SouthPaw700 said:
Still getting parts at this point. I got my 3ft of 30mm bearing rod on friday. This is the rod the linear bearings will ride on and allow the feeler and router arms to move up and down and side to side. I'm trying to decide what I want to use for rails now. Gemini just uses 2" steel tube and uses spindle rollers. This might be ok, but seems like it could be a little sloppy. I'm toying with the idea of getting 1" supported linear bearing rail, and open block linear bearings. This would be quite strong and quite precise.
Click to expand...

I agree. If you are building it, you will save enough to not have to cheap out. I would over build, and make all the overkill adjustments I could think of.
 
I picked up some supported linear rail and linear bearings for the y-axis of the duplicator. I think I'm going to run this rail down the middle and then run 2 supporting rails on either side that are made out of 2" tube. This way the linear bearings will keep the tolerances tight and the tube will keep it strong, plus I will save money not having to buy a pair of linear rails. This will also simplify the process of making the duplicator longer or wider because I would only need a single section of linear rail and 2" tubing, which would again be cheaper than buying twice as much supported linear bearing rail.

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Have you seen these?

http://www.youtube.com/watch?v=PUr5IFXNT0A

http://www.youtube.com/watch?v=mqUtlIP81rI

How are you going to do the two linked rotary axis?
 
How are you going to do the two linked rotary axis?
Click to expand...

For the rotating axis I will simple use two same-sized sprockets linked with chain, and on the other end, like something very similar to the live center tailstock on a wood lathe.

Unless you go very big time cnc a simple copy router is very much the way to go. They are very simple and easy to build and run.
Click to expand...

Yeah, cnc would definitely be overkill for my uses. As long as I can make decent copies with a tight duplicator (hopefully the linear bearings will help), then I will be happy for the time being :)
 
Ok, so we're about to get things underway here. I got the last of the linear bearings in the mail today. Here's a picture of the overall dimensions of the thing.

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Like I mentioned before I'm just going to run a single linear bearing length-wise to take lateral and rotational "slop" out of it. Running parallel to the length-wise linear bearing will be steel tube that I can run rollers over to take some of the weight, and to make sure it doesn't teeter-totter on the length-wise bearing.

This configuration will allow me to duplicate a piece of wood with dimensions approximating 42" x 12", which should be just fine for rifle stocks.
 
Just a thought on the power head, a few years ago at a close out
of a window and door manf., I picked up a air router, 1/4'', 3/8" and 1/2'
collets with it, about the size of a pop /beer can and it has lots of power,
I would think about the same as a 1 1/2- 2 hp electric.
I can't remember the brand, would have to look at it.
It would be very easy to mount up for something like this.
You need a big compressor thou, that could be the only drawback.
I have a 5h.p 2 stage commercial one .
re bits , you can get spirial solid carbide straight bits that are fairly long,
I think I have a 1/2" about 2-3 inches long.
Good luck with this.
If you want more info about the air router, pm me , I check late each night.
Marshall
 
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