Help working out the bugs

[Rick Lucrezi]

Just finished an order of 50 displays, with a 100 more in queue. There is a potential total order of 7000. Need help working out some bugs.
The main problem I am having is tear out. I am using Baltic Birch in the BB variety as BBB is cost prohibitive. I Have tried various combinations of Freud Industrial Blades and can not seem to get a perfect cut. The main area of trouble is on my Bosch Slider. The saw is a 12 inch, and never could get it to stop wobbling. Took all the washers down to a machinist, had everything trued up and still wobbles on start up. Had an adapter build for a 10 inch blade and problem solved. The stock needs clean cuts on both sides and the blade recommended for this just burns the wood. Various combinations of blades gets one good side.
This is mass production work, going to hire some guys so I am trying to make it fool proof. Can not expect a guy to stand at the saw for 8 hours and not push to fast or too slow on any given cut. I have 500 bucks into blades that just do not do the job. Need to know what the best choice is from guys or gals who do this every day in similar situations. This is the same material most drawer boxes are made of. Cabinet folks? What is the deal?
Have some other questions but do not want to overload this one first.

[Trent Shirley]

Is there tearout on top, bottom or both?
For the bottom you should be using a zero clearance insert to help minimize tearout.
If on top, you could use a piece of material there also help keep tearout down. Some scrap incrementally pushed over the material so that the edge to cut is covered will help prevent chipping. Perhaps even some tape would be useful.

[Glen Blanchard]

+1. A line of blue masking tape may be all you need.

[J.R. Rutter]

Per Trent's reply, If I were doing this without a jump saw with zero clearance top and bottom, I would cut as a sandwich with sacrificial scrap above and below (or whatever side the tearout is happening). Move the backer scraps about 1/4" for every cut. On the bottom, set up an outfeed spacer scrap as a stop, since it will not be as visible. The tiny offcut would have to be cleared each cut, but strategic DC hose might take care of it. I would also set some pneumatic clamps left and right of the blade with a foot pedal valve.

[Rick Lucrezi]

tape is my normal mode. The deal is, one display has 14 cross cuts with the birch. In a run of 50 displays, it would be too time consuming. I like the idea of the pneumatic clamp idea. Maybe if the clamps had wood connected to it to act as a backer that may help and solve a different issue as well. Was also thinking about a different saw. Scary but a saw that does not have to be restarted for every cut would work well. A lot of heat is generated by start up and my saw started smelling of wire burning. Other than that I was hoping a blade would be the solution.

[Mike Heidrick]

Check your fence faces - could be causing slight pressure on the side of the work that is burning.

Nice good old big RAS would handle this duty. Maybe multiple pieces at on cut depending on the saw and setup.

[Don Jarvie]

+1 on a Radial Arm Saw. Put a Chopmaster from Forest on it and no more chip out.

[Forrest Bonner]

I have solved the top tearout problem by doing a very shallow climb cut (on the pull stroke) followed by the full depth forward stroke. Any tearout on the bottom should be solved with a zero clearance insert.
Forrest

[Peter Kelly]

Find someone with a CNC to make the parts for you? A flat table machining center that is set up for nested based production will give you parts with zero tearout.

[Peter Quinn]

I don't think any blade will entirely solve your problems with the SCMS. You could look for a laminate flooring blade, which will have a triple chip design that minimizes tear out on delicate veneers and brittle surfaces like melamine, but Baltic birch is neither of those. It has some of the thickest face veneers going and is not particularly hard or brittle. May still help?

http://www.woodcraft.com/product/202...FcZx5Qod_yTuTQ

First step for me would be set the saw up perfect as possible, fence halves parallel, everything square and tight. Next step would be to make a sacrificial plywood table that bolts to the fence providing support from below and behind during the cut, which should minimize chipping. When this gets worn, move to a fresh location. Set the blade depth to not cut through this for strength. If the blade gets pitch on it, clean it. Dirty blades drag and chip, and all that glue on plywood can dirty a blade quick. As noted already, a very slight climb cut (back to front) which just breaks the face can be executed quickly and safely to minimize tear out on the face of delicate items or tricky grain, but having cut lots of BB I'd argue its not usually necessary. Check to see that that saws blade is not heeling. If the head is slightly sideways relative to its path of travel, it can cause most of the problems you describe. On a RAS this condition can be adjusted out, on a SCMS I suppose its not supposed to happen so I'm not sure it can be adjusted out or not on your model. Best fix may be a new saw?

On that note, If I were trying to get this job done cheap for the purpose of making money with slim resources out of necessity, I would try all of the suggestions in this and all the other posts previous. Some times you just have to make it happen with what you have. If you have other machines available, almost any other saw would be a better choice IME. A TS with a good sled, a GOOD RAS, certainly a sliding TS with scoring, or perhaps outsourcing to a CNC shop. Depends on your market and business model. If you are in the business of selling a wood product and wish to do so at the lowest cost per unit, it may make sense to seek out a CNC service for doing the cutting. If you have guys you want to keep employed as much as possible, or are in the business of selling labor AND wood products, eliminating the human factor from parts production may not make the most sense. No business equation is that simple.

Oh, you might try running a 10" blade on that saw to see if it wobbles less? BB is pretty dense as plywood goes and tends to slice a bit more like solid wood IME than most man made products. I have found 10" thin kerf blades such as used on most chop saws tend to wobble less than the larger 12" varieties. Or some of those large stabilizer washers may help? THey make the laminate blades in 12" too if necessary.

[Michael Peet]

Okay, well I'm one of the slowest workers anywhere, but I would do this with a table saw and crosscut sled. Clamp down a stop, turn the saw on, and crank out pieces all day long. My SCMS is strictly for rough-ish cuts.

Mike

[Tom Walz]

Call us if you want to talk to a cutting tool engineer.

No charge , of course.

Tom Walz

Carbide Processors

800 346-8274

[Jerrimy Snook]

I agree with all the above posts. I assume that you have been working with your local saw shop to find the best blade for this scenario. My recommendation would be something similar to the Forrest Chop Master mentioned above-- Full kerf, 0° or slightly negative hook/rake, no fewer than 80 teeth and no more than 100 teeth, and alternate face would help also... Perhaps a Tenryu Miter Pro.

Even if the SCMS is running true (less than 0.003" runout on the blade), and if there is a zero clearance insert, and if the saw is allowed to cut instead of chop the material, if the saw is running full speed when the cut starts, and if the top is scored, and if the blade remains sharp, and you are able to get perfect cuts every time, even with all this, your future employee would have to repeat your success. The ideal tool for this job would be either a CNC router or a jump saw.
A table saw and a sled may be more repeatable than the SCMS and may be something that you you already own.

[Rick Lucrezi]

@ Michael, Im starting to lean that way my self. The SCMS has not proven itself to me as the wonder tool I had hoped for.
@Peter Quinn, You hit on some good stuff. In regards to creating jobs, this has the potential to put 3 guys to work. Lots of good carpenters out there now unemployed. Win win to get these guys back to work. I had thought of the CNC and the whole thing could be done that way. I was told they have product in 7000 staores and want displays in every one. That would justify buying one myself. The reality is I do not have a facility to accommodate the material and final product for a order like that should they place it all at once. I had trouble with just 50. Lots of time spent handling material more than I wanted too.
There are some good suggestions here. The one I am trying first is a pneumatic clamp system with a roller bed and I am ditching the SCMS for a good RAS. I can reduce time by increasing my cutting width and if I can stack material that allows for a even greater time reduction.
Need a bigger shop.

[Peter Kelly]

The learning curve and costs associated with setting up a CNC are both pretty steep so be careful. If the parts are all relatively simple and not too large you could also go the over arm pin router/pattern/vacuum clamp route. Will still get you nice clean chip-free parts in any material.