Paging Thom 2 or anyone with an answer

[Bruce Cohen]

Thom,

Lee suggested I direct this to you as he informed me that you have more experience working with phenolic than he does.

I'm making this mortising jig and it requires a custom base plate for my plunge router* (see attachment). I've got the phenolic plate and all (yeah right) I have to do is cut it and drill out the center hole. Before I totally screw up a $12.00 plate, I figured I best ask you if my thinking if right, at least in reference to doing this.

A. Can I cut the plate to size using an 80 tooth carbide Freud blade on the 3100?

B. To drill out the large center hole, I have Forstner bits that are large enough to do the center hole (I have a Dewalt and the hole is less than the one shown (Porter-Cable). I guess a slow speed (300 rpms) on the drill press is good?

C. Any special speed I should use drilling the smaller holes and routing the slots on the base.

D. Now the really hard question. Do I leave the paper backing on after I'm finished, or does it get peeled off?

Thanks in advance for the help from you and anyone else

Bruce

[RodKirby]

Kirby opinion (based on experience with both acrylic and phenolic).

A. No problem.
B. Slow is good - will need a "fair bit" of down pressure in the DP - the idea is to get the bit to cut rather then just scrape.
C. Drill like you would for Hardwood (say 2,200RPM). Rout "normally" as for wood, keep the bit moving.
D. Leave the paper ON until everything is finished.

IMHO - the key to working with "plastics" is to keep the spinning tools moving, to avoid excessive heat.

[Bruce Cohen]

Rod,

Many thanks for the help, your thoughts are what i figured I was suppose to do, just needed to hear it from someone who has experience with the material.

Thanks,

Bruce

[cabinetman]

Just a slight bit of additional info. Hole cutters work better than forstner bits. A forstner bit designed to cut a flat bottom hole will be milling too much plastic. A good hole cutter (bi-metal) will work. Drill in a drill press, and have a back-up piece of wood under the plastic, and clamp down. Set up the hole cutter so the center drill bit is only slightly longer than the cutting edge of the hole saw. This helps to act like a continuing guide till the cutter exits the material. Ease the cutter down slowly into the material when starting.



"I'M NEVER WRONG - BUT I'M NOT ALWAYS RIGHT"

[RodKirby]

Just a slight bit of additional info. Hole cutters work better than forstner bits. A forstner bit designed to cut a flat bottom hole will be milling too much plastic. A good hole cutter (bi-metal) will work. Drill in a drill press, and have a back-up piece of wood under the plastic, and clamp down. Set up the hole cutter so the center drill bit is only slightly longer than the cutting edge of the hole saw. This helps to act like a continuing guide till the cutter exits the material. Ease the cutter down slowly into the material when starting.



"I'M NEVER WRONG - BUT I'M NOT ALWAYS RIGHT"

Makes very good sense.

Personally, I prefer to persevere with a Forstner to get a "cleaner" hole.

[Bruce Cohen]

Gee thanks guys,

Now I have to go and buy a 3" bi-metal hole saw and the arbor to go with it. Have you seen the prices on the Lennox?, not to mention Milwaukee or Starrett.

More toys, boy will the wife be pissed.

[kwgeorge]

I agree totally with the hole saw but would also add that you should use a lubricate when drilling the hole. These types of bits get very hot very quick and the residue from what you are drilling will only compound the problem. WD-40 will work well for this and will also act as a coolant so take it from a guy that spent a fair amount of time machining.

Ken

[Thom2]

Looks like I don't need to say a word here

[eezlock]

base plate

Thom,

Lee suggested I direct this to you as he informed me that you have more experience working with phenolic than he does.

I'm making this mortising jig and it requires a custom base plate for my plunge router* (see attachment). I've got the phenolic plate and all (yeah right) I have to do is cut it and drill out the center hole. Before I totally screw up a $12.00 plate, I figured I best ask you if my thinking if right, at least in reference to doing this.

A. Can I cut the plate to size using an 80 tooth carbide Freud blade on the 3100?

B. To drill out the large center hole, I have Forstner bits that are large enough to do the center hole (I have a Dewalt and the hole is less than the one shown (Porter-Cable). I guess a slow speed (300 rpms) on the drill press is good?

C. Any special speed I should use drilling the smaller holes and routing the slots on the base.

D. Now the really hard question. Do I leave the paper backing on after I'm finished, or does it get peeled off?

Thanks in advance for the help from you and anyone else

Bruce

[ATTACH]2214[/ATTACH]

Bruce, I would clamp that base plate down securely over a scrap piece of wood to the table and bore the hole
with a hole saw at a slower speed ( it helps to reduce the chance of overheating the plastic).Also, after all the holes are bored properly, remove
the paper backing before installing it on the router base. Eezlock