Question (WOODWEB Member) :
I know some of you run Diehl VS81ís. We purchased one last year, fully rebuilt and refurbished. It has consistently had problems completing a splice - the last 4-6" of the seam are either unbonded or, in brittle woods, destroyed. I made a movie showing what's happening - please, please take a few minutes to look at it. Any suggestions would be greatly appreciated. In particular, I'm wondering:
1. Has anybody else seen this? It's not described in Diehl's troubleshooting guides.
2. Is this a guide roller problem?
3. It's much worse with brittle or wavy veneers - do any of you routinely flatten certain species? If so, what do you use?
4. Any other ideas?
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From contributor V:
Diehl splicers are an excellent for thicker veneers and flat veneers. They use springs for the vertical pressure which makes fine pressure adjustments difficult. Most of the new splicers use pneumatic cylinders for the upper chain, heating bars and indeed roller pressure. This is critical for splicing thin veneers without damage. The ends of your splices not coming together could be from improperly jointed veneer or improper storage of jointed veneer. By this I mean veneer stored on a shop cart with the ends hanging over the end of the table. This causes the ends to dry out quicker than the middle resulting in open splice lines. Also glue application could be lighter on the ends depending on how the glue is applied.
As far as thin veneer, we have no problems doing thin anigre, sapeli and even thin recon material. With the new lighter springs thin stuff is no longer an issue for these machines. Is your machine Losier? Does it have composite chains?
To Contributor C: after posting the question I went out and did exactly what you suggested: remove the entire guide wheel assembly and run veneer on the chains only to see what happens. That worked ok, so then I spent some time fussing with the guide wheels. The setup suggested in the veneer manual (wheels parallel to the infeed guide) did not work at all. I ran 2" wide strips down each side separately, adjusting the guide wheels until it would feed without twisting or breaking. That seemed to solve the problem. I also fed up the feed speed (my guys liked to run the machine very, very slow for some reason). We ran walnut and sapele with the new setup. There was still a little cracking with the sapele (I think that one of the inner guide wheels is still very slightly off) but it's now working adequately well. One trick we tried a few times with sapele was to put a piece of veneer tape across the end of each leaf. This also prevented cracking. Since you asked, the machine was rebuilt by Lozier in 2009 and has the composition chains. He also put in digital controls, which are very nice.
Have you tried running your veneer from either end through your splicer? This will help determine if it's the veneer or splicer. If you run two leaves through you Diehl then take two more leaves and spin them end for end and run them and still have the same problem then your saw is ok and your splicer needs to be adjusted. If you have open seams at the front end as opposed to the rear like youíre having then I would say it's a cutting problem. But remember, veneer has a sort of memory which means regardless of how good your seam is it will resort back to its original shape, especially with buckled, brittle or wavy veneer which will cause problems at the Diehl or for that matter any splicer.
I have a Josting double knife and a Kuper FL splicer and still face these problems with buckled, wavy and brittle veneer. The answer to this problem is to treat the veneer with GF-20 and get it nice and flat. I had a qtr fig eucalyptus job last year and tried to run it up as is and had nothing but problems. I had to use a case of veneer tape to make the faces. Just recently I did another qtr fig Eucalyptus job (17,000 feet of it) and treated every last leaf. I did have the occasional problem here and there but nowhere near the magnitude of the first job. I would strongly recommend treating any brittle or buckled veneer prior to fabrication, but do it in small batches because once you treat it you have about an eight hour window to cut, splice and press your faces or the veneer will revert back to its original shape (memory). Remember, once you clip/veneer saw you books youíre committed so you don't want to get too far ahead of yourself as it can get rather expensive.
The Diehls are very finicky machines and require constant adjustment at both the front and rear. They are older machines and shake and vibrate. Although "reconditioned", they are not as good as they were when originally built - no machine is. Have you ever noticed that when the machine rep is making his pitch for his machine he has nice, flat veneer? Usually domestic veneer, cherry, maple, and oak non-brittle, wavy exotics. This is not to say that they are bad machines (if properly maintained and adjusted you can get quite a bit of production out of them).This may sound a bit strange, but every machine has its own personality, just like people. So in order to get your machine to produce for you, you have to get to know it, which means spending a little time with it and learning its little quirks and intricacies, something you won't find in any manual.
One thing I did notice on your video is the buckling of your veneer at both the beginning and the end of your leaves on the infeed side of your machine. This would indicate too much pressure on either your infeed rollers or your pressure bar/feed chains, or both. When you run veneer through your splicer, any splicer, be it a Diehl, Kuper, Ruckle, etc. edge glued or stitcher, the veneer should remain flat throughout the splicing process. Also, the feed speed looks a little slow which would cause distortion in your veneer like one of the other readers suggests.
Remember, youíre running your veneer through a very hot machine drawing moisture out therefore causing shrinkage. measure the width before and after you run your leaves and you'll see a difference. Anyway, I know this is long winded and there is so much more involved here but the bottom line is in order to adjust your machine and get it to cooperate. You have to start with nice flat veneer that's cut parallel and take it from there. Like the old saying goes, if you start with a problem, you end with a problem. It will take a little bit of time but you'll get it. Like one of the others noted, go back to the basics.