# Bits for dual-router duplicator....



## tobnpr (Feb 5, 2013)

Been a while since I've been on the forum (thanks to the great advice I received initially, haven't needed to!)

Business has grown to the point where I'm having a custom, dual-router gunstock duplicator manufactured. It will (obviously) allow me to cut two stocks at a time from the pattern stock.

However, 5 hp of router bits spinning in the same direction is concerning, so I plan to reverse rotation of one of the router motors- so that one will be climb cutting, and the other push cutting so that the torque will offset, and the machine will remain "controllable". FWIW, climb cutting is far from a no-no in this type of work...I've cut well over 100 gunstocks with the single machine using both climb and push cutting depending on the cutter and portion of the stock I'm working. Gunstock duplicators are an animal unto themselves....

Most bits will cut when used in a push or climb-cut application, so I can't see why this won't work with the standard, square-cut bits I use for 90% of my cutting.

Appreciate any concerns-especially from those of you that have run duplicators- that I might be missing.


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## kp91 (Sep 10, 2004)

Contact magnate.net they may have a solution for you.


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## Mike (Nov 22, 2004)

Mike, Whiteside manufactures specialty bits for reverse rotation. These will be better quality than the off shore built Magnate bits. I think this is an area where you do not want to short cut on the quality.

You may be interested in this website which produces colored plywood for applications like yours:

Cousineau Wood Products


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## gmercer_48083 (Jul 18, 2012)

Mike, I see why you want to reverse rotation, But I was taught that the nut that holds the blade...grindstone...or collet should tighten in the same direction as you would tighten it. For example a dual wheel benchtop grinder has a right hand thread on the right wheel and a left hand thread on the left wheel so that sudden changes in load will keep the nut tight. Something to think about.


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## Mike (Nov 22, 2004)

Exactly right Gary. Duplicators usually make the same cuts so the reverse will not work without a redesign. To run in reverse would require a different spindle.


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## tobnpr (Feb 5, 2013)

I get the concern about the direction of the nut tightening...

But I do not understand "reverse rotation bits"...

I regularly cut with the bit on both "sides" of the work- the side closest to me, and the opposite side of the work-away from me. There is no difference I can see between this (climb cutting, and push cutting) with the same bit.

Climb cutting with a "standard" rotation bit, would be no different that push cutting the same direction with a "reverse" rotation bit.

Bits cut either direction, which is tantamount to reversing rotation.


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## gmercer_48083 (Jul 18, 2012)

Mike, Climb cutting produces (lessons) router control, but the rotation will not encourage the collet to loosen.


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## tobnpr (Feb 5, 2013)

Yep, I do get that part, Gary.
I'll have to call Bosch and Porter Cable to see if they have any suggestions.

I prefer cutting with 1/2" shank bits when roughing out with a 3/4" straight bit, but I'm wondering if I can do a "workaround" by permanently fastening a 1/4" left handed thread collet chuck into the router's 1/2" with red loctite. Doubt such an animal exists- but I will not be deterred!  Then I wouldn't have to try to mod the router itself after reversing motor rotation. Time to burn some brain cells...


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## gmercer_48083 (Jul 18, 2012)

Mike, It sounds like it might be time to look into a CNC router. They seem to be pretty fast.


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## tobnpr (Feb 5, 2013)

Four (or five) axis CNC's would probably be cost-prohibitive, though they're coming down all the time.

If anyone knows of an "affordable" , and reliable, option- please pass it along.

Of course, I'd need to hire someone to teach me the code programming...


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## jdowney (Oct 9, 2010)

Left hand threads on the reverse spindle is fairly important.

Her-Saf makes left hand cut tooling, some of it carbide insert. The nice thing about their stuff for a multi-spindle machine is that the tool head screws on to a shank that stays in the machine. Makes bit changes easy, and you don't have to reset all the bit heights, just the stylus to the new bit height.

You can find 4 spindle Terrco machines pretty cheap these days. Mine was under $3500 by the time it was shipped and I bought some modern tooling. Big drawback to these machines is that they are big and hard to move (base is one piece).


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