[DesertRatTom]

Wow, ask and ye shall receive. Thanks for the alternatives.

 

[Cherryville Chuck]

When I first had the idea I thought it was going to be really simple but then I found out that all three sets of Forstners I have have metric sized shanks and I don't have a set of metric sized bits but it was a fairly quick work around to solve that. I used 3/4" ply and the ply is thicker than the Forstner rim is high and that is a requirement for making the jig. The bit I made the jig for has a 15mm shaft which is slightly smaller than 5/8" so I drilled a 5/8" hole through one thickness of the ply and then took it over to the cut off saw and roughly cut it through the middle of the hole. Then I drilled another piece of the ply with the bit I made the jig for. (Not sure what size it was, I never looked). With bit still in the DP and lowered into the hole it made I used some hot melt glue to stick the two other pieces of ply tight against the bit shaft. All that's left to do is clamp it in place. If you need a precise location then dimple the spot where it needs to go and you'll be able to feel when it's in place. The hole I drilled is as far as it would go without removing the jig and getting rid of the chips but it's no issue to relocate the jig to the same spot to drill deeper. The pictures tell the rest of the story.

 

[harrysin]

Could someone please explain to me why a jig is needed when using a Forstner style bit.

 

[Stick486]

free drilling w/o a DP and maintaining straight or angled for that matter...

 

[Cherryville Chuck]

I just finished building a vanity for a downstairs bathroom Harry where the drain pipe had to come out the side into the toilet's pump tank (macerator). I measured the location as accurately as I could but when I went to install the vanity I found it didn't fit flush against the wall which put the hole about 6mm / .25" off. I was using a hole saw but it is basically a continuous rim like the Forstner so the same type jig works. I clamped it onto the vainity and was able to enlarge the hole to where it needed to be. It would have been impossible to do that free hand.

 

[harrysin]

For that unusual job I fully agree, but when used in a drill press (what they intended to be used in) I have never found any difficulty drilling multiple holes vertically and in the correct spot.

 

[harrysin]

In my early post I forgot to mention that a few years ago I bought this set of sawtooth Forstner style bits off Ebay, I can't remember what they cost but I do remember that it was cheap! Unlike the much earlier smaller set from Carbar-tec which were hopeless, these work extremely well but even so if I have a Carbide tipped one of the same size required, then that is what I use.

 

[TenGees]

Harry, that set looks very much like one of my cheap sets, only mine came in a fancy wooden box with plexi windows. Mine came with the 'Mastercraft' (Canadian Tire) brand name. I like them but then I've never experienced 'good' bits.

That set of stepper bits also looks identical to my 'Mastercraft' cheapies... great for drilling plexi.

 

[Cherryville Chuck]

For that unusual job I fully agree, but when used in a drill press (what they intended to be used in) I have never found any difficulty drilling multiple holes vertically and in the correct spot.

Harry I was going to reply back when I saw this that 99% of the time I also use a drill press when I use a Forstner. A few times I've used them freehand, for drilling plug holes I think. However, getting them started without the bit skating around on the surface, especially the larger sizes, can be quite tricky. That jig is just another weapon in the arsenal to get jobs done. If someone needed to make a very accurate hole in a location where a drill press is impractical then they now have the idea for a quick and cost free jig that will get the job done for them.

 

[MT Stringer]

Off-hand, this is all I came up with without my coffee. I believe you could also make one somewhat similar, but out of wood.
https://www.amazon.com/gp/product/B...CIMEA&linkId=8a53319edbb22bc72e9a1e3414580046

I never buy sets of bits or the like. I prefer to just buy the one I want, then later buy whatever else I want, one at a time.

I have one of these. Not the best but it did help me guide the bit.

 

[MT Stringer]

For a jig, I simply cut a hole in a piece of 2x material (on the drill press) that I could clamp in place. Might not work for every situation, but it did help guide the bit.

Note: Check out the picture. I was repairing a goof up.:surprise: I had lost focus and pulled the router out of the hole while it was running, and before retracting the plunge! It quickly tore up the hole and broke the bit. :frown:

The repair worked great.