Spiral Upcut?

[tomwassmer]

Hi everybody! 

I'm wanting to make some hardboard templates to cut out multiple large parts using meranti marine plywood (ranging from 1/4" to 3/4"). Once my templates are complete, do you have any recommendations on router bits to trim my plywood parts to the final shape? I'm assuming a spiral bit? Should the bearing be on the top or bottle of the bit?

Thanks!

[pkinneb]

I like Whiteside router bits and and prefer spiral with top and bottom bearings. If I had to choose I would probably choose a spiral top bearing bit.  

[drzaius]

Yes to the above. A top bearing, upcut spiral will have less tear out on the bottom & the template will help to minimize it on the top. The spiral will give a better cut than a straight cut bit.

[tomwassmer]

Thanks guys. I appreciate the input! I'll check into Whiteside bits.

[gee-dub]

I agree that top/bottom bearings are great since you can follow the grain direction.  For ply I would use a spiral compression bit.  With bearings would be great for your thicknesses.  Without bearing can save you some dough but, your templates would have to be made to take the template collar into account.

 

Compression bits make a clean cut from the top and the bottom on veneered plywoods and substrates.  If you only have one show side, a downcut spiral would do you.

[jussi]

I have the whiteside udc9112. Works great and produces a smooth finish even on endgrain and/or figured wood.  Only downside is the large diameter doesn’t allow for tight spaces if you have a small curves. Infinity makes a similar one as well that you can get in wider variety of sizes.  I plan on trying out one of the 1/4” shanks in the future

[tomwassmer]

Thanks again guys. I definitely would like to stick to bits with bearings so I don’t have to deal with making patterns that allow for a collar. The large diameter of the 9112 won’t be an issue for this project. The compression bits look really awesome but as you’ve warned, are a bit pricey. I’ve decided what I’ll do is see what kind of results I get with a straight-knifed flush trim bit that I already have in my collection. If the results aren’t acceptable, I’ll spring for the compression bit.