Finishing the Ends of Cedar Chair Slats

      Woodworkers suggest ways to automate end finishing of pieces. October 4, 2007

I am automating my shop. I recently bought a Unimat Gold Moulder, and will upgrade my CNC machine and Omga op saw in the near future.

One area that I have not found an automated solution for is finishing the ends of my seat slats. These are cedar (wrc) slats 2.5 inches wide x 1 inch thick (moulded to .94 actually). The slats range in length from 12 inches to 44 inches with the vast majority 17, 20, and 23 inches long.

The finish is simple. We are smoothing the end (80 grit) from the saw cut and putting a slight chamber/bevel (perhaps 1/16 inch) on one edge or vertice of the end. The chamber is to prevent splintering over time which would occur if the part was left square.

Currently we handle each part individually. We use a vertical 48 inch belt sander and touch each end and then flip and touch again. We use a fence to insure the part stays square on the end.

We put the slight bevel on the end vertice using an angle jig that is on the table of the belt sander. After touching each end we slip into the angle jig and do the bevel. We can do about 4 to 8 slats a minute depending on the operator. The time includes pulling the part from a stack and putting it on a new stack. We process about 10 to 20,000 pieces a month.

I am thinking about a shaper with a power feeder and using a bardo sanding wheel. Keeping the slats together while feeding should prevent tear out. Keeping parts square to the fence or the tool might be a challenge.

We would need to run the parts through twice, once for each end, which means handling the parts twice and more operator time (which I do not like). I would need to buy a shaper and feeder or sanding wheel machine for this application.

I am not sure if a machine exists that will do both ends at once for varying lengths, which would cost under $30/40K. I assume a double end tenon machine might do this job, but may be overkill? Any ideas to minimize this last operator intensive process would be appreciated.

Forum Responses
(Solid Wood Machining Forum)
From contributor D:
I do a lot of odd jobs for a flooring manufacturer. Mostly radius bull nose and sort run tee moulding. Just yesterday I was standing in front of the end matcher and was amazed how fast this machine squared the stock and put a tongue and groove on the end of each board. The operator said it was only moving at half speed. Wow! I think that this type of machine would make short work of your slat problem.

From contributor T:
Friulmac makes a machine that is typically used for in-line end-matching of flooring and for matched rail and stile cabinet parts. I think it would do exactly what you are looking for and cuts with a climb cut (with a backer block), which should give you an excellent finish. Even on cedar, it would do both ends in one pass (two movements) and does not need an operator once the setup has been completed. The machine is a Randomat E. The last one we purchased was around $90k + tooling, but I have seen them used for around $70.

From contributor O:
I was in the cedar furniture business for a few years. We used a small double end tenor to do what you are doing by hand. No double handling.

From the original questioner:
The double end tenonor... How much material does it need to take off? My process now is I cut a 20 inch piece (finish length), mould the piece, then do the ends on a sander which removes less than 1/32 counting both ends. So I end up with a nominal 20 inch piece.

I have seen pictures of the tenoner, but have not run one. My understanding is they use saw blades, which I assume would have to remove material above what I am doing now. Would I have to cut the parts fat, then run through the tenoner? Would one put sanding heads in the machine or cut fat and have the tenoner finish the length?

From contributor O:
The Randomat actually uses more of a shaper spindle design and a climb cut on the wood. You can take off as much material as you need. We typically run wide-plank flooring and are taking 5/16" by the time we put the tongue on and 1/16" on the groove end (obviously the groove itself is deeper than that). The Randomat is different than a traditional tenoner in its design.

From the original questioner:
Thanks everyone for the direction. Sounds like the tenoner is the way to go. I will contact my sales reps and start talking to them about a tenoner.

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