Help (achieving proper bit depth using guide bushings on a router)>>>

[Kirk Butler]

:confused:


I'm new to the world of woodworking & recently purchased my first router. I went w/ the RidgidR29302, mainly cause it came w/ both a fixed and plunge base as well as the price. Additionaly, I've purchased the PC4210 dovetail jig.

My problem is this:
With the bushing guide in place (and locknut secured), I cannot set the bit to the desired depth (only able to set to about 1/4" deep).
When I lower the depth adjustment down, the process is stopped @about 1/4" deep(bit tip below bottom lip of guide). While lowering bit it APPEARS that the depth is stopped b/c the collet nut is to big and bottoming on the locking nut for guide. I [I]THINK[I] if the collet nut was only bout 1/2", that would allow for another 1/2" of depth.

FYI, I'm using the 1/2"dovetail bit w/ a normal 1&1/2" shank length that came w/ the jig. Also, the template is 1/4" thick and the guide bushing is only 3/16" thick so, it is not a matter of the bushing needed to be grinded down a little as some guide bushings come w a wider guide lip.Is it possible that I need to use a 1&3/4" length shank bit when using guide bushings on my particular router?



Thoughts?

Has anyone else had any experience in this kinda problem?

I hope this makes sense.


TYVM in advance for any help!

[Terry Beadle]

If I'm understanding your situation correctly, it boils down to not having enough bit to cut as deep as you need. A router bit needs to be about 1/8th of an inch from the bottom of a collet to be properly mounted. However, with your plate and jig, the bit can't reach enough. Therefore you need to pull some more of the bit out of the collet and hope it will keep the bit tight..or make a thinner jig, or buy a longer bit. Pattern bits are usually longer in expectation of the need to include a bearing surface on the jig. Also the bushing insert may/will need to add a little to the use of bit length so that it can perform in a steady manner.

Be careful as to how much you pull the bit out if you attempt it. Keep your cuts very thin, as in 1/16ths at a pass until you get a good handle on the collet bit mating strength.

Good Luck!

[Kirk Butler]

Thanks for the input Terry!

I actually thought about pulling the bit out 1/2". This would allow for desired depth.

Anybody else tried this? Sound safe?

I don't suppose there will be much harm in trying as long as I take very shallow passes at first.

Just seems strange that the bit that came w/ the jig doesn't have a longer shank (1&3/4") if that is what is needed???

[glenn bradley]

You want at least 1" of shaft in the collet for 1/2" shaft bits and I prefer a little more for 1/4" shaft bits. If by following these safety guidelines your bit is not long enough, get a longer bit. the cost of a bit is far less than the cost of an "incident" at 20,000 RPM. You will see many "dovetail jig" specific bits and their increased length is one of their "specifics".

http://holbren.com/search.php?mode=search&page=1

http://www.rockler.com/product.cfm?page=19586&filter=leigh

http://www.woodcraft.com/Product/2021089/21671/Dovetail-Bit-for-Leigh-Jig-12SH-1316D-114CL-8A-3516OL---CMT-Part-81870611.aspx

[Kirk Butler]

Check/Roger

Thanking you guys!!!

What a great forum. So glad I found the site!!!!!

[Rick Potter]

Since you say you are new to this, let me add to the above advice. Do not put a router bit into the collet all the way. Two reasons....first, if it is a short shanked bit you might be trying to tighten on the small radius where the shank and cutter meet. Second, when a bit is tightened it is pulled into the collet a bit. Always bottom a bit, then pull it out 1/8" or so before tightening.

Rick Potter

[dave toney]

As far as how deep to have the bit in the collet, I have a different take.
If you unscrew the collet and look at the tapered cone that holds the shank you will see how far you MUST have the shank of the bit into the collet, this is usually about 5/8" - 3/4". once the bit is inserted fully to the depth of that cone you will have all of the gripping power you will ever get.
In other words, pull it out as far as needed as long as there is enough shank to be fully gripped when inserted, it will hold the bit just as well as if it is fully inserted.
Runout and vibration can be magnified with more shank exposed, but with 1/2" shank bits that are not a large diameter this is not usually a problem.

[Mike Henderson]

I do the same as Dave described. I take the collet nut out and put my bit into it only as far as the bottom of the tapered cone. I figure anything more is not useful for holding the bit.

Mike

[Jim Rimmer]

Check/Roger

Thanking you guys!!!

What a great forum. So glad I found the site!!!!!


Good advice so far. And, Welcome to the Creek. If you think you got $6 worth of advice, consider being a contributor. :)

[Greg Hines, MD]

Are you using a bit designed for your jig? Most jigs require certain bits to work with.

An alternative would be to cut the bushing thinner. Standard Porter-Cable bushings are about 1/2" deep, and you can get some depth by hacksawing (or your metal working choice) the bushing thinner. I put up with it for a while then got a set from Woodcraft that are significantly thinner, like 1/4".