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| Thickness sanding . . . thinner exit points http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=25766 |
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| Author: | James Orr [ Fri Jan 29, 2010 7:59 pm ] |
| Post subject: | Thickness sanding . . . thinner exit points |
I have the Performax 10-20 drum sander. The camber is adjusted so that I have uniform thickness from left to right whenever I use it, but the pieces are always noticeably thinner at the ends that exit the sander. The picture is a scrap I ran through to give you an example. My guess is that it's from the weight of the wood pulling the end further into the drum since it's not supported by both hold down springs. Would getting the extension tables solve this? Has anyone else experienced it? |
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| Author: | MRS [ Fri Jan 29, 2010 8:42 pm ] |
| Post subject: | Re: Thickness sanding . . . thinner exit points |
Yes! I had the same problem with my 10-20 until i bought the extension tables. In my opinion they are totally necessary and should be a part of the sander. They shouldn't cost extra. Without them the I feel the sander is useless...Mike |
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| Author: | JohnAbercrombie [ Fri Jan 29, 2010 8:54 pm ] |
| Post subject: | Re: Thickness sanding . . . thinner exit points |
James- I think you are correct in assuming that the wood is 'springing up' once the infeed pressure roller isn't holding the wood down. I'm not sure an outfeed table would prevent this- I'm assuming that you are holding the work at it exits from the machine? EDIT: Corrected by a Performax user! I find that lighter cuts as the thickness approaches the 'target' help a bit with this problem. Cheers John |
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| Author: | Heath Blair [ Fri Jan 29, 2010 10:05 pm ] |
| Post subject: | Re: Thickness sanding . . . thinner exit points |
extension tables would definitely help. i dont use them and dont have any problems though. i almost always hold the piece down against the outfeed side of the conveyor and sometimes even gently pull upward on the end of the piece while doing so. you might try adjusting your rollers for a little more tension too. by the way, and not that it matters, but the thinner end on either the leading or trailing edge is called "snipe." |
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| Author: | Morgan [ Fri Jan 29, 2010 10:39 pm ] |
| Post subject: | Re: Thickness sanding . . . thinner exit points |
I leave a little extra at the ends, seems to help, along with some of the other suggestions. Morgan |
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| Author: | Zach Ehley [ Fri Jan 29, 2010 10:52 pm ] |
| Post subject: | Re: Thickness sanding . . . thinner exit points |
I have a Craftsman 18-36 which is the same machine as the Grizzly G-458. It has a sort of leaf springs to hold down the piece instead of a rollers. I have two things that happen. What you experience of thinner at the beginning and end as well as getting a little divot when the wood hits the second spring and it sometimes catches before if goes under the spring. Light passes seem to lessen the effect you are getting. The two problems are related as when the wood gets thin, the roller seems to want to lift it up. This causes the second problem as it lifts up and hits too high on that second spring. The only thing I could think of is making some sort of vacuum backer board that holds the wood down flat as the drum tries to lift it us when the wood is thin. Haven't tried it yet, just a theory at this point. |
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| Author: | Mike Lindstrom [ Fri Jan 29, 2010 11:04 pm ] |
| Post subject: | Re: Thickness sanding . . . thinner exit points |
On my 22-44, the conveyor belt bows up in the middle. It's not a problem with anything with mass, but it lifts something as light as a top. When I'm sanding really thin stuff, I use one hand to hold the conveyor flush with the table. I don't know if it helps, but it makes me feel better and it cuts down on the drum stripping the texture off the conveyor. Mike |
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| Author: | Pete Brown [ Fri Jan 29, 2010 11:46 pm ] |
| Post subject: | Re: Thickness sanding . . . thinner exit points |
JohnAbercrombie wrote: James- I think you are correct in assuming that the wood is 'springing up' once the infeed pressure roller isn't holding the wood down. I'm not sure an outfeed table would prevent this- I'm assuming that you are holding the work at it exits from the machine? EDIT: Corrected by a Performax user! I find that lighter cuts as the thickness approaches the 'target' help a bit with this problem. Cheers John Any wood thin enough to flex compresses the conveyor belt slightly because of the pressure exerted by the sanding drum, and the trailing end of the work springs upwards when it no longer has similar pressure applied to it by the infeed roller. A carrier board, e.g., a piece of MDF surfaced with 80-grit abrasive paper, helps avoid this. Cheers Pete |
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| Author: | James Orr [ Sat Jan 30, 2010 1:30 am ] |
| Post subject: | Re: Thickness sanding . . . thinner exit points |
Filippo, I'm pretty sure. The taper isn't side to side, it's snipe at the back end of the piece. It's dead even side to side, but I'm interested in looking up the straight edge/battery method. Thanks for the feedback, everybody. |
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| Author: | WudWerkr [ Sat Jan 30, 2010 9:23 am ] |
| Post subject: | Re: Thickness sanding . . . thinner exit points |
I have the same problem with my sander . and as has been mentioned , I start out with slightly longer blanks to solve the issue . |
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| Author: | Michael Lloyd [ Sat Jan 30, 2010 6:56 pm ] |
| Post subject: | Re: Thickness sanding . . . thinner exit points |
I will follow the wood with another top or side, a piece of scrape if doing only one piece. No gap between pieces. |
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| Author: | Eric Reid [ Sat Jan 30, 2010 9:14 pm ] |
| Post subject: | Re: Thickness sanding . . . thinner exit points |
In addition to all the causes mentioned above, I think snipe also happens because at the very end of the cut the downward force of the drum is distributed over a smaller and smaller area. (Think of the cross section when half of the drum is no longer on the board.) Michael's suggestion should fix that if you have enough scraps of the right thickness and hardness (and long enough to not get shot back at you by the sander). In drum sanding nut and saddle blanks, I use a carrier board and vary the speed of hand feeding to minimize the snipe--fast at the ends, slow in the middle. |
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| Author: | Daniel Minard [ Sun Jan 31, 2010 2:54 am ] |
| Post subject: | Re: Thickness sanding . . . thinner exit points |
To prevent thinning like that, I lift the board as it enters the infeed roller & once it is engaged by both rollers, reach over to the outfeed side & lift until the wood is past the sanding drum. I mean... really lift the end. Bend the wood up a bit to force the unsupported end down on the bed of the sander. You can use the same method to minimize snipe on a planer. The thinner the wood, the more likely you are to get the problem you describe. |
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