help with box finger joint on router table

[trojan62]

hi everyone,
i hope someone can help whos a bit more knowlegable than me.
as above, ive made different jigs for my router table to cut these joints and the same result, terrible.
it would be ok i suppose if i knew what i was doing.
anyway, ive seen the videos online, printed out the pdfs and made these jigs, but for the life of me i cant seem to get this right. i use a straight bit in the table as i dont have a spiral bit yet, plus they seem expensive.
anyhow, what im asking is, is there foolproof and easy way to cut these joints and could someone give me a few tips.

thanks

chris.....

 

[Steve Maskery]

Have you seen mine?
http://blip.tv/workshopessentialscom/fi ... ig-3225447

S

 

[RogerP]

I built a copy of Steve's jig and it works very well - thoroughly recommended.

 

[baldpate]

Assuming you're using jig(s) which work on the same principle as Steve's (I've seen at least one other design - could you confirm?), perhaps you could tell us more precisely what's going wrong. If it's problem of fit, I think the most likely problems are either that the width of the registration peg isn't exactly the same as the width of the hole routed by the bit (what Steve calls a "goldilocks fit") or that there is slop in the fit of the slider which runs in the router table slot. Did you ever get a good workpiece fit at the test stage?

 

[Steve Maskery]

I built a copy of Steve's jig and it works very well - thoroughly recommended.

Thank you Roger, the cheque is in the post


Baldpate - All good points.
S

 

[monkeybiter]

I made a bog standard jig and the results were quite poor, the joint had to be hammered together, it looked crap and would probably have split. I then made a loose adaptation of Mr. Maskery's design and the results are effortlessly perfect. I made it to fit a mitre guage for quickness and so I can use it on the table saw as well as the router table.
I think the keys to it's success are the screw adjuster for the slot pitch and the fit of the registration key.

 

[Eric The Viking]

Ditto Mike (Monkeybiter).

I've gone a stage further and adapted Steve's jig to make octagonal joints. That was an epic in itself, but there's no doubt the principle works very well, and I've an octagonal experiment nearly finished to prove it.

Mine runs on an MDF sled on the router table, with a very long 3/4" key in the mitre slot. Although the key is softwood, I lubricate it with Liberon and/or candle wax and it doesn't seem to stick, nor wear much. The indexing peg is old-growth oak, which seems to be OK.

I used cheap MDF though for the parts: big mistake. The material is simply not strong enough to take slots for adjuster screws, etc. You end up with washers punching through the soft inner part of the MDF, rather than tightening everything up!

The only issue I can see, and it'll be common to any router table jig, is tearout. The back fence helps a lot, but you need to both keep the cutters clean and make sure the shavings don't build up in the blind slot in the fence. It seems to be worse if the cutter can't exit the workpiece easily, and it's certainly worse if the cutter isn't kept very clean. Other people use Oven cleaner, but I find you can use WD40 or xylene on a piece of kitchen paper, along with a suede brush, to clean whilst the cuttter is still in the router, so you don't disturb the height setting (yes, I pull the power plug, EVERY time!).

That's a cue for another Maskery modification I think, putting a big DX hole in the router plate for use when doing housings, finger joints, etc. That'll keep until I have time to rebuild the table though.

E.

 

[WoodMangler]

I built a copy of Steve's jig and it works very well - thoroughly recommended.

+1