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Crosscut Sled--What did I do wrong?
Having read so much about how useful a good crosscut sled was, I finally
built myself one this weekend. I followed the basic instructions described he http://www.imaging.robarts.ca/~amulder/wood/j.sled/ The base is 3/4 inch birch plywood. The front & back are 2x4 common lumber. The runners are birch plywood slices, carefully taped to fill the slot and minimize wiggle. The table seems to slide smoothly and easily over the blade but when I went to make a few cuts with it (3/4" cherry, not a problem for my saw usually) the blade bound and wanted to kick the whole thing back at me. What was my mistake? Thanks in advance, Dan Grieves |
#2
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I recommend a harder material for the runners. Oak, Maple, Steel. I am
guessing your runners are flexing and causing your sled to not go in a straight parallel line to the blade. It will work better also if you mount the runners into a dado so that there will be no flexing. "Daniel Grieves" wrote in message ... Having read so much about how useful a good crosscut sled was, I finally built myself one this weekend. I followed the basic instructions described he http://www.imaging.robarts.ca/~amulder/wood/j.sled/ The base is 3/4 inch birch plywood. The front & back are 2x4 common lumber. The runners are birch plywood slices, carefully taped to fill the slot and minimize wiggle. The table seems to slide smoothly and easily over the blade but when I went to make a few cuts with it (3/4" cherry, not a problem for my saw usually) the blade bound and wanted to kick the whole thing back at me. What was my mistake? Thanks in advance, Dan Grieves |
#3
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On Tue, 09 Nov 2004 00:13:32 GMT, "Leon"
wrote: I recommend a harder material for the runners. Oak, Maple, Steel. I am guessing your runners are flexing and causing your sled to not go in a straight parallel line to the blade. It will work better also if you mount the runners into a dado so that there will be no flexing. If it's not the flex that Leon suggests, maybe the runners aren't square to the blade slot? This would move the slot from side to side as the sled travels along. With the saw shut off can the sled move smoothly over the blade for the full travel? I lay the runners in the slots with glue on them, lay the panel on, place some weights, and add screws after the glue sets. The blade slot dosen't get cut until after the face(s) are added, then the rear face is squared to the slot and glued. The saw itself is the perfect jig for aligning the runners. Dadoing would add a whole bunch of extra work, in my opinion. Since I usually make sleds and jigs when the need arises, I tend to simplify them as much as possible. My smaller sleds don't even have a front fence. I've used ash, red & white oak, birch, and maple for runners. All worked fine. Barry |
#4
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In article , Ba r r y
wrote: If it's not the flex that Leon suggests, maybe the runners aren't square to the blade slot? Or maybe the blade isn't square to the miter slots... |
#5
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"Dave Balderstone" wrote in message tone.ca... In article , Ba r r y wrote: If it's not the flex that Leon suggests, maybe the runners aren't square to the blade slot? Or maybe the blade isn't square to the miter slots... I hope it is not.. :~) Maybe parallel is what we are looking for here. |
#6
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On Tue, 09 Nov 2004 00:47:42 GMT, "Leon"
wrote: "Dave Balderstone" wrote in message stone.ca... In article , Ba r r y wrote: If it's not the flex that Leon suggests, maybe the runners aren't square to the blade slot? Or maybe the blade isn't square to the miter slots... I hope it is not.. :~) Maybe parallel is what we are looking for here. RIGHT! G I'm sure both of us mean parallel. If the blade were square to the runners or slots, I'm sure we'd get all kinds of neat problems. At least _I_ always know what I mean. Barry |
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In article , Leon
wrote: I hope it is not.. :~) Maybe parallel is what we are looking for here. Oops. Yeah, parallel, that's it... ;-) |
#8
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#9
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On Mon, 8 Nov 2004 15:59:16 -0800, "Daniel Grieves"
wrote: Having read so much about how useful a good crosscut sled was, Not from me - they're dangerous bloody things. A UK HSE inspector will usually throw a wobbly if he sees one too (they're having a downer on "emerging blade" cuts these days). Throw it away now and build a crosscut _BOX_. This is similar, but it has a top too. The sides are tall enough to keep your fingers away from the blade and there's a wide strip (often transparent) across the top, covering the blade from the top direction. This also helps to stiffen the box, avoiding the sort of flex and binding in the baseplate that you're getting. You can also (if you make a box) use a baseplate of thin Masonite, rather than thick plywood. If this should choose to bind, the force is minimal and it's unlikely to lift or throw. There should be closed-ended tunnels at the ends of the slot too, so that the whole blade can be "swallowed" without protruding. Make the ends of them thick enough to survive running into the blade from time to time. -- Smert' spamionam |
#10
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"Andy Dingley" wrote in message ... Throw it away now and build a crosscut _BOX_. This is similar, but it has a top too. I thought a picture would help. Here is a fancified version of what you are talking about. http://billpentz.com/woodworking/cyc...an/Image20.jpg Bob |
#11
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Bob wrote:
"Andy Dingley" wrote in message ... Throw it away now and build a crosscut _BOX_. This is similar, but it has a top too. I thought a picture would help. Here is a fancified version of what you are talking about. http://billpentz.com/woodworking/cyc...an/Image20.jpg Bob Is that a MuleCab fence? (I'm thinking of getting one.) -- Mark |
#12
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"Mark Jerde" wrote in message news:vLXjd.101$z_4.78@trnddc07... Bob wrote: Is that a MuleCab fence? (I'm thinking of getting one.) Sorry, I don't know, Mark. The link belongs to someone else. I just happened to see it an thought it was useful to post here. Bob |
#13
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On Tue, 09 Nov 2004 01:07:32 +0000, Andy Dingley
wrote: On Mon, 8 Nov 2004 15:59:16 -0800, "Daniel Grieves" wrote: Having read so much about how useful a good crosscut sled was, Not from me - they're dangerous bloody things. A UK HSE inspector will usually throw a wobbly if he sees one too (they're having a downer on "emerging blade" cuts these days). Throw it away now and build a crosscut _BOX_. This is similar, but it has a top too. The sides are tall enough to keep your fingers away from the blade and there's a wide strip (often transparent) across the top, covering the blade from the top direction. This also helps to stiffen the box, avoiding the sort of flex and binding in the baseplate that you're getting. ... and if the problem is that his runners are flexing, the only thing he is going to accomplish by that is adding mass to that which will be thrown back at him. So, how do you actually get something *into* this totally safe box? and how do you hold anything steady with all these safety devices hanging about the thing? I personally use a clamp to hold the piece I'm cutting, thus accomplishing two things: 1) it makes sure the piece does not slip while being cut and 2) it keeps my fingers safely away from the blade. You can also (if you make a box) use a baseplate of thin Masonite, rather than thick plywood. If this should choose to bind, the force is minimal and it's unlikely to lift or throw. There should be closed-ended tunnels at the ends of the slot too, so that the whole blade can be "swallowed" without protruding. Make the ends of them thick enough to survive running into the blade from time to time. I've found that a simple block wood attached at the back center of the sled accomplishes the same thing without the complexity of a "tunnel" |
#14
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On Mon, 8 Nov 2004 15:59:16 -0800, "Daniel Grieves"
calmly ranted: Having read so much about how useful a good crosscut sled was, I finally built myself one this weekend. I followed the basic instructions described he http://www.imaging.robarts.ca/~amulder/wood/j.sled/ The base is 3/4 inch birch plywood. The front & back are 2x4 common lumber. The runners are birch plywood slices, carefully taped to fill the slot and minimize wiggle. The table seems to slide smoothly and easily over the blade but when I went to make a few cuts with it (3/4" cherry, not a problem for my saw usually) the blade bound and wanted to kick the whole thing back at me. What was my mistake? IF your sled runs fine with the blade up + no wood, and there is no slop in the runners, and the blade is new or very sharp: Most probably, you didn't hold the wood firmly against the back fence or didn't hold it down, perpendicular to the blade. Either will cause binding. -- The State always moves slowly and grudgingly towards any purpose that accrues to society's advantage, but moves rapidly and with alacrity towards one that accrues to its own advantage; nor does it ever move towards social purposes on its own initiative, but only under heavy pressure, while its motion towards anti-social purposes is self-sprung. - Albert Jay Nock - http://diversify.com Web Programming for curmudgeons and others. - |
#15
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Larry Jaques wrote:
IF your sled runs fine with the blade up + no wood, and there is no slop in the runners, and the blade is new or very sharp: Most probably, you didn't hold the wood firmly against the back fence or didn't hold it down, perpendicular to the blade. Either will cause binding. To help hold the wood in place I put down strips of "Skid Guard Safety Tape" on the back and bottom of my sled. You could also glue strips of sandpaper but I already had the self-adhesive strips. It made all the difference for keeping the piece being cut in place. -- Mark |
#16
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On Mon, 08 Nov 2004 17:09:04 -0800, Larry Jaques
wrote: Having read so much about how useful a good crosscut sled was, I finally built myself one this weekend. I followed the basic instructions described he http://www.imaging.robarts.ca/~amulder/wood/j.sled/ The base is 3/4 inch birch plywood. The front & back are 2x4 common lumber. The runners are birch plywood slices, carefully taped to fill the slot and minimize wiggle. The table seems to slide smoothly and easily over the blade but when I went to make a few cuts with it (3/4" cherry, not a problem for my saw usually) the blade bound and wanted to kick the whole thing back at me. What was my mistake? one thing to check is that your 2x4 front (the one the wood rides against) is straight. if it's concave you could get that kind of binding. it really should be made of stable dry material. I gave up making them out of 2x. these days I make them out of baltic birch ply... |
#17
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one thing to check is that your 2x4 front (the one the wood rides
against) is straight. if it's concave you could get that kind of binding. it really should be made of stable dry material. I gave up making them out of 2x. these days I make them out of baltic birch ply... Kiln dried, VG doug fir. Jointed flat & square. Shellac and wax. 1/2" BB ply. Oak runners, or Delta purchased runners, if I'm particularly lazy or in a hurry. Patriarch |
#18
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All kinds of dancing around this one, but this answer is incorrect in one
important aspect. Blade parallel to the miter slot is the first problem. This can cause the blade to bind, even though it's going to produce a square cut. Are you lifting splinters from your plywood? one of the sure signs of non-parallel on a tablesaw or heel on a radial. If you have your runner(s) tight, make sure they're tight all the way through the cut, though it makes no difference in the world if they are tight in the miter slot. *What makes a difference is that it references one or the other side consistently.* This means straight, and I mean straight as in no light when you set it on your reference. Some sled builders recommend deliberately undersized runners on either side, pinching the sled by riding the inside of the slots or out. Keeps binding to a minimum by providing a bit of dust clearance. "Larry Jaques" wrote in message news On Mon, 8 Nov 2004 15:59:16 -0800, "Daniel Grieves" calmly ranted: Having read so much about how useful a good crosscut sled was, I finally built myself one this weekend. I followed the basic instructions described he http://www.imaging.robarts.ca/~amulder/wood/j.sled/ The base is 3/4 inch birch plywood. The front & back are 2x4 common lumber. The runners are birch plywood slices, carefully taped to fill the slot and minimize wiggle. The table seems to slide smoothly and easily over the blade but when I went to make a few cuts with it (3/4" cherry, not a problem for my saw usually) the blade bound and wanted to kick the whole thing back at me. What was my mistake? IF your sled runs fine with the blade up + no wood, and there is no slop in the runners, and the blade is new or very sharp: Most probably, you didn't hold the wood firmly against the back fence or didn't hold it down, perpendicular to the blade. Either will cause binding. |
#19
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"Daniel Grieves" wrote in message ... Having read so much about how useful a good crosscut sled was, I finally built myself one this weekend. I followed the basic instructions described he http://www.imaging.robarts.ca/~amulder/wood/j.sled/ The base is 3/4 inch birch plywood. The front & back are 2x4 common lumber. The runners are birch plywood slices, carefully taped to fill the slot and minimize wiggle. The table seems to slide smoothly and easily over the blade but when I went to make a few cuts with it (3/4" cherry, not a problem for my saw usually) the blade bound and wanted to kick the whole thing back at me. What was my mistake? Thanks in advance, Dan Grieves Did you check the speed of feeding and proper blade for crosscutting? |
#20
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On Mon, 8 Nov 2004 15:59:16 -0800, "Daniel Grieves"
wrote: Having read so much about how useful a good crosscut sled was, I finally built myself one this weekend. I followed the basic instructions described he http://www.imaging.robarts.ca/~amulder/wood/j.sled/ Suggestion. It looks like the "handle" is over the blade. Make it with one either side for safer "handling". |
#21
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Ok, first of all...Thanks to everyone who took the time to respond. Here's
what I can gather from your various responses: 1) Make sure my saw blade is parallel to the mitre guage slots. Is there a more accurate way to do this than just building a simple T-square type thing that I would ride in the slot and make sure it touches the saw blade equally at all points? 2) Double-check that there's no play in my runners. Will do. 3) If 1 & 2 don't eliminate the problem, I will replace the 2x4 with something more stable to prevent the sled from flexing. 4) If 3 doesn't work, add a top to provide even more stability. I'm guessing it would have to be something pretty hefty (but clear) to be workable. 5) I guess I'm a little confused on 1 point. I thought the design of the sled was to hold the stock against the front but Larry made it sound like the wood runs against the back edge. Which is correct? (When building my sled, I only checked the front board for perpendicularity to blade.) Thanks again, Dan |
#22
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If I understand you correctly, you are pushing the wood against the front
side of the sled. Before you do steps 1 to 4, try putting the stock to be cut against the back of the sled. Closest to where you stand. That is the correct place. Of course check the back side for perpendicularity to the blade. HTH, Dave 5) I guess I'm a little confused on 1 point. I thought the design of the sled was to hold the stock against the front but Larry made it sound like the wood runs against the back edge. Which is correct? (When building my sled, I only checked the front board for perpendicularity to blade.) Thanks again, Dan |
#23
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Dave wrote:
If I understand you correctly, you are pushing the wood against the front side of the sled. Before you do steps 1 to 4, try putting the stock to be cut against the back of the sled. Closest to where you stand. That is the correct place. Either front or back is fine. In some ways it makes more sense to be pushing everything forward... ;-) IIRC Kelly Mehler's table saw book shows both front and back aligned crosscut sleds. I don't have the book checked out from the library so I can't check for sure. ;-) My understanding is the Europeans favor the front models in both jigs and sliding table construction, while US woodworkers favor the back. -- Mark |
#24
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On Tue, 09 Nov 2004 18:16:10 +0000, Mark Jerde wrote:
Either front or back is fine. In some ways it makes more sense to be pushing everything forward... ;-) I don't think I understand this. Unless the bed of the sled is very narrow, if you put the workpiece against the back of the sled, aren't you going to be hanging over the blade? That would make me nervous. And if the bed is wide enough to accomodate larger workpieces, isn't a lot of the sled going to be hanging precariously off the front of the table before you make the cut? |
#25
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On Wed, 10 Nov 2004 19:33:23 -0600, Ray Aldridge
wrote: On Tue, 09 Nov 2004 18:16:10 +0000, Mark Jerde wrote: Either front or back is fine. In some ways it makes more sense to be pushing everything forward... ;-) I don't think I understand this. Unless the bed of the sled is very narrow, if you put the workpiece against the back of the sled, aren't you going to be hanging over the blade? That would make me nervous. And if the bed is wide enough to accomodate larger workpieces, isn't a lot of the sled going to be hanging precariously off the front of the table before you make the cut? I think we should clarify terms. The front of my saw is the part that the operator's belt buckle hits when cutting. The front fence of my sled is the fence that gets to the outfeed table first when cutting. If the sled is completely sitting on the saw, the rear fence is nearest the front of the saw. When I make a sled, I rarely square the front fence, only the rear. The front fence usually exists only to stiffen the sled. Some of my smaller sleds don't even have a front fence. That said, I just about always cut with the work held against the rear (reference) fence, pushing it through the blade. Therefore I think Ray and I are on the same page, I don't know which fence Mark is calling the "front" fence. G Barry |
#26
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#27
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On Tue, 9 Nov 2004 08:48:57 -0800, "Daniel Grieves"
calmly ranted: Ok, first of all...Thanks to everyone who took the time to respond. Here's what I can gather from your various responses: 1) Make sure my saw blade is parallel to the mitre guage slots. Is there a more accurate way to do this than just building a simple T-square type thing that I would ride in the slot and make sure it touches the saw blade equally at all points? If you have a dial indicator, you can mount it to the miter gauge so it touches the blade. Check the reading at the front, rotate the blade to the back, and check the reading again. Ed Bennett, one of the Wreckers here, builds a fancy set for checking all the tools in your shop, butcha gotta have a crowbar if you're like me. The $6 Harbor Freight indicator works just fine. You choose. The video he has put together is great, and a really good value: $1.96 delivered to your door. http://www.ts-aligner.com/newindex.htm 2) Double-check that there's no play in my runners. Will do. Good. 3) If 1 & 2 don't eliminate the problem, I will replace the 2x4 with something more stable to prevent the sled from flexing. I used 1/2" Baltic Birch ply and put a piece of 1x4" oak on both ends. It flexes only when I put a 6-8' stud on there to hack off. g 4) If 3 doesn't work, add a top to provide even more stability. I'm guessing it would have to be something pretty hefty (but clear) to be workable. If you want to be EU safe and don't want to see what you're cutting. (Pretty soon they'll have thought police there, too.) 5) I guess I'm a little confused on 1 point. I thought the design of the sled was to hold the stock against the front but Larry made it sound like the wood runs against the back edge. Which is correct? (When building my sled, I only checked the front board for perpendicularity to blade.) So we're clear, I call the end which hits the saw first the front. Because it's cut last, the back is closer to your body while feeding the sled through. I nestle the board up against the backer board closest to me. The front board is there to hold the two cut halves of the sled together. The back is what should be aligned with the blade. Did that help clarify things for you? I've noticed a couple times that vibration in the saw (Dina can't pass the -flat- nickel test due to an old jaw injury on her motor pulley, but it's only about 1/4" off. caused the board to float out about 1/8" and I got a bind when I started the cut. I pay more attention now to both finger and board placement. ------------------------------------------------------------- * * Humorous T-shirts Online * Norm's Got Strings * Wondrous Website Design * * http://www.diversify.com ------------------------------------------------------------- |
#28
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My way of checking that the blade is parallel to the miter gauge slot is as
follows: MAKE SURE YOUR TABLE SAW IS UNPLUGGED WHILE PERFORMING THIS PROCEDURE. I bought a cheap ($13.00) dial indicator from Harbor Freight, marked and drilled a hole in the end of a 1X3 and mounted the dial indicator to it. I clamped the 1X3/dial indicator assembly in my miter gauge (mine has a hold-down but you can use a regular clamp) and marked a tooth on the blade that was "set" toward the miter gauge. I held the bar of the miter gauge tight against one side of the slot and slid the rig back and forth while rotating the blade to make sure the dial indicator tip was in contact with the same spot on the marked tooth both front and back By doing this, I was able to reduce the arbor alignment error to only .003 inch. I could have gotten it closer with a little more effort but since the blade itself had more than four times the runout, I figured that was good enough. I bought the dial indicator after struggling for three days...and many test cuts...to set up my power miter box using a method similar to what you described. "Daniel Grieves" wrote in message ... Ok, first of all...Thanks to everyone who took the time to respond. Here's what I can gather from your various responses: 1) Make sure my saw blade is parallel to the mitre guage slots. Is there a more accurate way to do this than just building a simple T-square type thing that I would ride in the slot and make sure it touches the saw blade equally at all points? |
#29
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That dial indicator is on sale in the stores right now for $6.99. A nice
magnetic base is just a little more. "Chuck Hoffman" wrote in message m... I bought a cheap ($13.00) dial indicator from Harbor Freight... |
#30
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I still have those feeler gages for those spark plug things we used to
change all the time in cars. If I care how far off is off. Use your combo square riding the slot. Touch good, no touch bad, it's a go/no go situation, since any error is bad. "Dave" wrote in message news:1F8kd.20953$5K2.11374@attbi_s03... That dial indicator is on sale in the stores right now for $6.99. A nice magnetic base is just a little more. "Chuck Hoffman" wrote in message m... I bought a cheap ($13.00) dial indicator from Harbor Freight... |
#31
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On Tue, 9 Nov 2004 16:55:21 -0500, "George" george@least wrote:
I still have those feeler gages for those spark plug things we used to change all the time in cars. If I care how far off is off. Use your combo square riding the slot. Touch good, no touch bad, it's a go/no go situation, since any error is bad. Exactly. Barry |
#32
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On Tue, 9 Nov 2004 08:48:57 -0800, "Daniel Grieves"
wrote: Ok, first of all...Thanks to everyone who took the time to respond. Here's what I can gather from your various responses: 1) Make sure my saw blade is parallel to the mitre guage slots. Is there a more accurate way to do this than just building a simple T-square type thing that I would ride in the slot and make sure it touches the saw blade equally at all points? that's the basic idea. you also want to account for any runout in the blade itself, though. the way to do that is to pick a spot on the blade near the rim and mark it with a felt tip pen. use that spot for all of your measurements. raise the blade all of the way up to increase it's length above the table. rotate the blade so your mark is near the front and take a measurement of the distance from the blade to the miter slot. rotate the blade so the mark is near the back and take another measurement. compare the two measurements. it sounds like it's time to post my sled again on ABPW. look for it there. |
#33
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On Mon, 08 Nov 2004 18:59:16 -0500, Daniel Grieves wrote:
Having read so much about how useful a good crosscut sled was, I finally built myself one this weekend. I followed the basic instructions described he http://www.imaging.robarts.ca/~amulder/wood/j.sled/ I constructed that a sled using those plans a few months ago. I modified things slightly, and it works excellent (although took a few iterations to get it working well). I'd recommend replacing your runner material with something harder. I started with hard maple. These worked ok, but not great. I recently upgraded to steel bar, available at the local BORG. This has made a huge difference in overall stiffness and ease of sliding the sled. One problem I had with the wooden runners was that they were very slightly warped, or curved, so if the sled was square at the front of the cut, it was slightly off by the end. This did cause some binding. I'd also recommend attaching a piece of 2x4 or 2x6 protruding out the back. This is similar to the 'tunnel' someone else mentioned, but a lot simpler. The blade goes into the 2x4, and I always know where it will end up after a cut. I don't have to worry about visually checking where my hand is - I can do it by feel. Try replacing the runners, and see if that helps. A working sled is well worth the time invested. Chad |
#34
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"Chad Bender" wrote in message news One problem I had with the wooden runners was that they were very slightly warped, or curved, so if the sled was square at the front of the cut, it was slightly off by the end. This did cause some binding. Maybe this is too obvious a question. Did you mill the wood before using it as runners? Bob |
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