# Half-blind dovetail jig ??'s



## woodnthings (Jan 30, 2009)

Once and forever I need to know the answer to: What size bushing to use in the parallel 1/2" slots of a half-blind jig, and what size and degree bit. The Jet instructions call for a 7/16ths guide bushing and a 1/2" -14 degree bit.
The Woodstock jig instructions, p 5 PDF, also call for a 7/16ths bushing and 1/2" bit. By my own admission I was using a 1/2" guide bushing (my mistake) and it wouldn't work. When I switched to a 7/16th bushing, it worked. Some here have advised me and others to use a guide bushing that exactly fits the slots: 1/2" bushing for 1/2" slots. I think that applies only to THRU dovetail jigs, not half-blind. Yes? 
I'm going to try to attach the chart downloaded with the Woodstock instructions p. 5 PDF . Here's the confusing part: They are calling for a 1/2" bit for use with a 7/16th bushing for using a 7/16th template. Notice bushing and template are the SAME size! Now the real confusion: To use a 9/16ths template, they call for a 7/16ths bushing and a 1/2" bit.
Looks like I pitch out everything that isn't 7/16ths!


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## bobj3 (Jan 17, 2006)

Hi Bill

see PDF file below,see page 5, not all dovetail jigs are the same 


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woodnthings said:


> Once and forever I need to know the answer to: What size bushing to use in the parallel 1/2" slots of a half-blind jig, and what size and degree bit. The Jet instructions call for a 7/16ths guide bushing and a 1/2" -14 degree bit.
> The Woodstock jig instructions, p 5 PDF, also call for a 7/16ths bushing and 1/2" bit. By my own admission I was using a 1/2" guide bushing (my mistake) and it wouldn't work. When I switched to a 7/16th bushing, it worked. Some here have advised me and others to use a guide bushing that exactly fits the slots: 1/2" bushing for 1/2" slots. I think that applies only to THRU dovetail jigs, not half-blind. Yes?
> I'm going to try to attach the chart downloaded with the Woodstock instructions p. 5 PDF . Here's the confusing part: They are calling for a 1/2" bit for use with a 7/16th bushing for using a 7/16th template. Notice bushing and template are the SAME size! Now the real confusion: To use a 9/16ths template, they call for a 7/16ths bushing and a 1/2" bit.
> Looks like I pitch out everything that isn't 7/16ths!


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## woodnthings (Jan 30, 2009)

HI Bob, You sent me the exact chart I quoted from that got me confused. I wasn't able to figure out how to attach just that page or I would have. The Woodstock intructions are far more complete than the JETS. My JET jig is the same as the Woodstocks as far as the slot dimensions go I'm almost certain. So I am still not clear about this. The JETS even recommend the same size bits and bushing as Woodstock. So that's all good, no confusion there. It's just when switching templates slot sizes I get lost. Woodstock uses thee same 1/2" bit for ALL 3 sizes and the 7/16ths bushing for ALL 3 sizes, according to their chart. So I'm off to the shop to try it out. I still want to use 1/2" or 3/8" thick stock, but maybe not possible with half-blinds? I'll see. I may end up with a 1/4" bit or 3/8ths.?


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## woodnthings (Jan 30, 2009)

Hey guys. Sorry but I'm going to post my own post, I'll then be "posted". The Woodstock instructions are correct. However bit height is very critical, and my old PC 690 is a loose goose for height adjustments. Woodstock says use a 7/16ths bushing and 1/2" -14* bit for all 3 templates, 7/16ths, 1/2" and I'll go out on a limb and say also 9/16ths, but I haven't tried that one yet. I'll have to tear down one of the other setups (I have 2 JET Dovetail Jigs, as some may know from my previous posts) to do it and I'm not in the mood...may never be! It's nice when you can answer your own posts, and it hopefully may help someone else with this issue. Bill


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## hardwoodjoint (Feb 12, 2009)

Thanks for uploading that manual. I've lost mine and it explains alot.

Cheers
Tony


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