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wide belt sander snipe7/29/15
I have a Powermatic 25" single head wide belt sander and i am getting just a tad bit of snipe that is only visible after finish. I am talking maybe jut a few thousandths. If enough time is not spent with the Dynabrade then it is noticeable. I have never recieved a complaint and dont even think most people notice unless it is sitting on a flat bench under light. However i would like to adjust to correct the problem. I just dont want to start adjusting without knowing what i am doing. So i am asking what causes snipe on a widebelt and what parts do i adjust to eliminate it?
We have a powermatic 25" dual drum sander, so the adjustments may be similar.
Typically, ours will start to snipe if one of two things occur:
1. The feed rollers are too loose. If the material isn't held tightly to the rubber conveyor, it will hit the sanding belt too high, resulting in snipe.
2. The table becomes unparallel with the drums.
Even when these two issues are adjusted, severely bowed wood can still end up with snipe as the bow will not sit flat on the table surface. This may be less noticeable with a single head wide belt and a platen.
Assuming you have set the bed level with the head and the pinch rolls per factory manual and that you don't have any slack in the bed supports, try feeding the doors through at slight angle so the rails don't hit the contact drum all @ once.
I have had this sander for over 5 years used almost everyday and it is rock solid. The bed is 100% parallel with the head.
I wonder if the platen is too low? Or not low enough? I dont know.
My sander was made in 1997 and since i have had it i have had zero problems.
Leading or trailing edge? Are you using both the platen and drum or just the drum. The part with the snipe will tell you what caused it. Just align the mark with the sanding contact and the edge of the part will correspond to the offending party.
Just be aware that narrow warped parts will have issues in your machine no matter what. Once the warped part clears the hold down rollers it will push itself into the head more than when it's being controlled.
Thanks for the reply. I looked into it more today and it is the trailing edge of the doors that have the snipe. It is about 2.5"from the end of the doors. So does this mean the outfeed rollers are too high?
On a diffirent note, i do want to buy a SurfPrep sander sometime.
Oh and i forgot to add i do not run any warped parts at all. I pride myself on a flat door. I flatten all parts on the jointer.
You want about .060" of pressure on the hold down rollers at most. Often I used .040" to .050", but I can't see your machine and feel the strength of the roller springs.
If you use a block of wood and bring the table up until you have light pressure between the block and the sanding drum, then you can drop the conveyor .060". Then you look for how much pressure you have on the rollers. They should be just lightly touching the block.
Usually your situation is from too much pressure on the front rollers. You can see the correlation between the sanding drum and the hold down roller from the length of the mark on the part.