Self Centering Jig

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Mark's Wood Chips
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Self Centering Jig

Post by Mark's Wood Chips »

I'm drilling lots of cribbage boards for a customer who provides blanks made from exotic woods. The blanks can vary slightly in width so I made the pictured jig to accommodate them. The drilling tool path indexes off the top center of the blank. I wanted to share the idea because this jig can be used for many applications. It's a simple hinged rectangle that pivots in the center of both ends, making a parallelogram as it pivots. The blank is inserted against a stop, the jig is tightened against the work and held in place by slotted clamps that secure both the blank and jig. The photos show the empty jig, the blank in the jig, and the drilled board with a couple of extra end pivot arms. I hope that you find it useful.
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TReischl
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Re: Self Centering Jig

Post by TReischl »

Very cool jig! Have not seen anything like that before.
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Re: Self Centering Jig

Post by Rcnewcomb »

A very simple yet elegant design!
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Re: Self Centering Jig

Post by MarkJohnston »

Very nice jig indeed.

Can you tell me what toolpath, bit, speeds and feeds you use to drill all the cribbage boards?

I'm having a lot of burning when I drill that many holes. I have a porter cable router so the slowest I can run is 10000 RPM.
Just curious how you are doing the holes?

Thanks for showing us the jig.

Mark

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Re: Self Centering Jig

Post by 4DThinker »

Very clever indeed! Just curious if it centers horizontally too?

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Re: Self Centering Jig

Post by edwan »

Great idea! Thanks

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Re: Self Centering Jig

Post by Mark's Wood Chips »

MarkJohnston wrote:Very nice jig indeed.

Can you tell me what toolpath, bit, speeds and feeds you use to drill all the cribbage boards?

I'm having a lot of burning when I drill that many holes. I have a porter cable router so the slowest I can run is 10000 RPM.
Just curious how you are doing the holes?

Thanks for showing us the jig.

Mark
I use a drilling tool path, 0.125" drill bit, 60 ipm feed, 40 ipm plunge, total depth 0.5", 0.28 peck, 0.1" safe Z, 8500 rpm. I can get my PC router to turn at 8500 rpm with a Super PID speed control set in Mach3. I sharpen the bit periodically and clean it in concentrated citrus cleaner with an old toothbrush. That stuff works wonders on router bits, saw blades and any other tool that picks up sappy gunk at a fraction of the price of blade cleaners.

Mark

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Re: Self Centering Jig

Post by zeeway »

+1. Elegant design. Well done.

Angie

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Re: Self Centering Jig

Post by Mark's Wood Chips »

4DThinker wrote:Very clever indeed! Just curious if it centers horizontally too?
This one does not but I think a guy could add a couple more linkages to accomplish it, or simply make another one mounted vertically over the top of the horizontal jig.

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Re: Self Centering Jig

Post by 4DThinker »

I can see a great advantage to a jig that centers both horizontally and vertically if you alway use the center of your material for the 0,0,0 origin point.

4D

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Re: Self Centering Jig

Post by MarkJohnston »

Thanks for the reply on the cribbage hole. I will give it a try.

Mark J

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Re: Self Centering Jig

Post by KeithW »

I drill mine with a .125 straight flute EM, with drilling to .375.

Router (Hitachi) full speed - no burning. Sometimes use peck drilling, sometimes not.

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Re: Self Centering Jig

Post by 4DThinker »

I've had good luck using a 1/8" (good quality) drill bit in a 1/8" collet adapter to drill arrays of 1/8" holes. Turn the router down to its slowest setting. Set my plunge speed to the fastest the machine would allow, clearance Z to .05, and peck drilling if the holes were very deep. Machine acceleration limits won't let the travel between holes get very high, so greatest gain comes from plunge speed and minimal clearance Z.

4D

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Re: Self Centering Jig

Post by Mark's Wood Chips »

4DThinker wrote:I've had good luck using a 1/8" (good quality) drill bit in a 1/8" collet adapter to drill arrays of 1/8" holes. Turn the router down to its slowest setting. Set my plunge speed to the fastest the machine would allow, clearance Z to .05, and peck drilling if the holes were very deep. Machine acceleration limits won't let the travel between holes get very high, so greatest gain comes from plunge speed and minimal clearance Z.

4D
What do you think the RPM is at your lowest setting? I can go much slower but I based the RPM by the look of the chips. I do get occasional darkening inside holes of real sappy wood and, after running hundreds of blanks, I have to wash the collet, nut and drill. I use a Drill Doctor to sharpen the drill and the drill is probably sharper than new, lasting for thousands of holes.

I have tried using an end mill and an end mill that I ground to a point, neither of which did as well as a standard 118 degree point drill.

Mark

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Re: Self Centering Jig

Post by 4DThinker »

Mark's Wood Chips wrote:What do you think the RPM is at your lowest setting? I can go much slower but I based the RPM by the look of the chips. I do get occasional darkening inside holes of real sappy wood and, after running hundreds of blanks, I have to wash the collet, nut and drill. I use a Drill Doctor to sharpen the drill and the drill is probably sharper than new, lasting for thousands of holes.

I have tried using an end mill and an end mill that I ground to a point, neither of which did as well as a standard 118 degree point drill.

Mark
I don't remember off hand but I'll guess 10,000rpm on the 1 (out of 6) setting on the speed dial. Dewalt 2.5hp router. I haven't done a lot of hole drilling, but one of my students wanted a 3/4" x 3/4" spaced array of 1/8" holes across a 24" x 48" pieces of BB plywood. I started with a 1/8" spiral upcut 2-flute carbide bit but switched to a coated drill bit when that router bit started smoking holes. The drill bit pulled chips out faster as it drilled and looked no worse for wear at the end.

4D

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