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Old Dog needs help!
Posted: Thu Feb 16, 2017 7:39 pm
by dgreen810
I made a new cross cut sled to cut at 45 degrees. Try as I might so far can't seem to cut a 45 at 90 degrees. The sled with the table tilted to 45 seems awkward to begin with but I am wondering if it's me or do others have the same problem??? I am using a stop block so I am reasonably sure the board is not moving and clamping it is not feasible unless I make some hold-downs on the fence. Any suggestions??
In the past I used the miter gauge and had pretty good luck but thought a sled would be more accurate and easier to repeat, guess that what I get for "Thinking"
Don G
Re: Old Dog needs help!
Posted: Thu Feb 16, 2017 7:50 pm
by JPG
IIUC what you are attempting, I think it should work.
However the sled 'fence' is critical.
I am assuming the blade to miter gauge slot is correct.
How is the 90° off and can you alter it with the fence?
Re: Old Dog needs help!
Posted: Thu Feb 16, 2017 8:22 pm
by dgreen810
James
I am trying to make some boxes using 1/2" Maple, Walnut, and Pecan that is around 3 to 4 inches wide. The cut is a good snug 45 degrees but the cut invariable is not producing a 90 degree cut perpendicular to the length of the board. It would seem the board as it's being cut is being sucked into the blade or being pushed away but I sure don't see how??
I know with a table saw this is not a problem but for some reason with the table tilted at 45 I can't get a good cut.
Don G
Re: Old Dog needs help!
Posted: Thu Feb 16, 2017 10:13 pm
by rjent
How tight is the bar in the miter slot? It looks like your sled is "cocking" slightly.
Just a guess .... :/
Re: Old Dog needs help!
Posted: Thu Feb 16, 2017 10:56 pm
by JPG
How does the other side look against the square(square against the same edge).
Does the work piece have wind?
I assume you are only feeding until the piece is cut through. Do you then pull it back before removing the workpiece from the sled?
For this to work, the sled must be flat. The workpiece must be flat and held tight to the sled. The sled must remain tight to the table. The fence must be 90° to the blade. The runners must be 90° to the fence.
It looks like it starts out correctly, then about half way skews.
BTW you are checking with the square to the edge that faced away from the sled fence when it was cut.
Re: Old Dog needs help!
Posted: Fri Feb 17, 2017 7:50 am
by Hobbyman2
I had issues with the main shaft moving on my MKV...a few thousandths is all it takes,, I now rough cut the wood and just use the disc sander to true up the cuts.
If you have a dial indicator you may be able to check the sled .
I got one from a place called harborfreight , it may not be the highest quality however it is accurate enough for my work.
Hobbyman2
Re: Old Dog needs help!
Posted: Fri Feb 17, 2017 8:15 am
by nuhobby
+1 on Rough-cuts following by disc-sander truing. This is my favorite way for perfect miters.
Chris
Re: Old Dog needs help!
Posted: Fri Feb 17, 2017 9:07 am
by dusty
You may not have said this but I got the impression that you can achieve a 90° cross cut if the table is not tilted.
This would indicate to me that your sled is properly positioned with respect to the blade so long as the table remains horizontal. Runners are good, fence is good, sled itself is good.
When you tilt, you are not so fortunate. Tilting the table and the work piece can be a challenge. To overcome that challenge, I clamp the work piece to the sled or to the fence. How, can be difficult - depending on what facilities were incorporated in to the sled. Looking at yours, the only suggestion would be to clamp to the fence.
Re: Old Dog needs help!
Posted: Fri Feb 17, 2017 9:19 am
by JPG
Look for any deviation from straight line motion(side slip) as the sled nears the back of the table. It likely is slipping to the right(down the table slope).
Re: Old Dog needs help!
Posted: Fri Feb 17, 2017 9:29 am
by dusty
If you suspect that the sled is slipping as it is pushed forward, clamp a straight edge onto the table to serve as a runner on the low end of the sled. This would be for fault isolation only.
Do you have two runners on the sled?