Cutting marine ply gingerbread

[edp]

Have been asked to quote on a large run of 8" wide gingerbread fascia cut from 1/2" marine ply, Would really appreciate any suggestions as to type of bit and feed speeds - am looking for minimum sanding (read none)after cutting. I have had some problems in the past cutting this type of marine ply with tearout on the face veneer which takes forever to fill and sand. The minimum radius in the rather simple pattern is 1/4" so a 1/2" bit would be ideal for the cut. The top edge of the fascia is straght, the bottom 2 easy joined radii with a heartshaped pierced cutout on 8" centers 2" from the top edge. I have a PRT96 with a good vacuum hold down system so holding the sheets is not a problem. I have a feeling a ply boatbuilder would know about this sort of thing.

[davidallen]

I haven't tried marine ply but on other types, a downcut shear or spiral has given good results. I've tried a compression bit but unless you can cut the full width, you start with an upcut bit which tears the edge.

da

[srwtlc]

I've used an Onsrud 3/8" compression spiral with good results. The upcut portion is only 3/16" I believe, so you can easily keep the downcut flutes below the surface with a full depth cut. Feed speeds depend on what you're using, router or spindle. Make a lead in to your contour so the upcut entry is away from your finished edge to start. I have a PRT w/PC so I'd start at 1.5/sec and adjust on the fly from there.

I'm sure that marine ply will be tough on bits so keep the rpms somewhere where the bit doesn't get to hot and I like to use a shot of this stuff between cuts too.

Scott

[edp]

Many thanks for the input on this job. The run is 54,000 feet so I really need to get the tooling and feed rates right. Once again, thanks for the input.

Ed

[dhunt]

Thanks for the tips.
This project to cut 1 mile+ of decorative facia board is due to start in a week's time,
consuming about 140 sheets of 1/2 inch marine ply.
Any more tips re. tooling and feed rates in the cutting of marine ply
would be v.welcome as we gear up for this run.
Thank you.

DH

[NSchlee (Unregistered Guest)]

David, Is this domestic (fir) marine ply? You might look into using 12mm BS1088 Okoume. This material is a higher quality than domestic marine ply. Much less chip out when cutting, no voids, no veneer joints, no patches (footballs).

Neal

[dhunt]

Unsure just what we will be supplied with.
Stock is yet to be trucked in from our local supplier,
but will be sure to let you know just what we get to work with, once it arrives.
Thanks for your interest: will keep you posted
most likely before the end of the week(?).

[gene_marshall]

have you thought about extira?

[elcruisr]

David,
If you want a good clean cut edge top and bottom try a compression spiral. I cut up thousands of parts in ply and I'm sold on Onsruds 60 series (and there are many other options out there as well). I use mostly 60-121 single flutes. You need the short upcut for 1/2" material. I can run at 8 to 10 inches a minute at 17,000 rpm with a spindle, don't know if you have a spindle or not. If your facia has alot of small details your feed speed will be slower no matter what you set and the speed will neet to be lowered to keep chipload correct.

Eric

[gerald_d]

Eric, is that 17 000 for a 1/4" or 3/8" bit? (I don't know the Onsrud numbers)