Bevel Sled for the Shopsmith

[tdubnik]

As I mentioned in my Christmas Project post, I haven't taken much time to keep up with the forum or do any posting. Since things have calmed down a little, I'm playing a little catch up.

In the table project from the Christmas post, I mentioned that the aprons were beveled 45 degrees in the corners. The aprons were about 8" wide and I wanted to have good tight fittting joints. I tried cutting them with the miter gauge with the hold down grip, but was never satisfied with the fit. It seems that I couldn't hold everything perfectly while making the cut.

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I almost always have some hardwood runners to fit the Shopsmith miter slot (I make them a dozen or so at a time) so I decided a bevel sled was the answer.

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This is the completed sled with a plywood fence and toggle clamp hold down. The base is simply some MDF. I made the sled so it would be trimmed to zero clearance on the first cut. You might also notice that the fence is slightly adjustable and I'll go into why I did this in a minute.

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This picture shows the table at 45 degrees, the blade set and the sled trimmed.

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I mentioned that the fence is adjustable and I made it that way because even though I get perfectly square cuts when the table is at 90 degrees, they are always slightly off at 45 degrees. I am quite sure this must be due to the table being either slightly higher or lower at the back as compared to the front. This would not affect a 90 degree cut but it does affect a bevel cut. Rather than take the time to get the table perfect, I chose to make the fence adjustable so I could compensate for this. It worked perfectly.

Continued in next post.

[tdubnik]

[attach]15530[/attach]

This shows the underside of the sled with the runner attached. I do use a little trick to attach runners. I first make sure my base is square and mark the position of the runner. I then locate the runner in the proper position and clamp a square to keep is straight. While holding the runner against the square I wick a little thin CA glue under the runner. Five seconds later the runner is temporarily fixed in position allowing me to drill and countersink for the screws. This trick works every time and the runner never moves when I secure it.

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This shows everything all set up and ready to cut.

The total time to make this sled was under an hour and I will often make a one use jig if it improves my accuracy or help eliminate errors.

I'll try to post my frontier log jigs within the next couple of days.

[Gene Howe]

Nice job on that sled. Thanks for posting it. I'll be using your idea in the future.
Do you sneak up on the correct angle for the fence (trial and error)? How do you know when the first cut is correct?

[JPG]

Nice job on that sled. Thanks for posting it. I'll be using your idea in the future.
Do you sneak up on the correct angle for the fence (trial and error)? How do you know when the first cut is correct?

Holding a square up to it would be informative.

Trying to get my mind around the tilt introduced error.

I agree the hinges must not be parallel to the table top(front to rear).

Only thing I can come up with is shimming between the table and trunion.

How much 'error' are you observing at 45&#176]SURE [/B]the miter gauge is accurate(square to the blade) and the miter slots parallel to the blade. I would verify those before even thinking about shimming the table/trunion. Is the table top perpendicular to the quill both side to side and front to rear in drill press position?

Unfortunately all these things interact!!!

If the table/trunion is not parallel, the 45 tilt and the drill press position should BOTH be be 'off' the same direction.

[tdubnik]

Nice job on that sled. Thanks for posting it. I'll be using your idea in the future.
Do you sneak up on the correct angle for the fence (trial and error)? How do you know when the first cut is correct?

I did basically sneak up on the correct angle. When I made my first cut and checked the beveled edge with a square, I could see about 1/16" of light at the leading edge of the cut. This told me I needed to move the end of the fence farthest from the blade back just a hair. I left the pivot point tight, loosened the lock knob a little and bumped the fence with a small hammer. I then made another cut and repeated until I was satisfied.

I then cut two boards, layed them flat on a table, butted the bevels together and taped them. I then folded them together and confirmed that my angle was exactly 90 degrees.

[tdubnik]

Holding a square up to it would be informative.

Trying to get my mind around the tilt introduced error.

I agree the hinges must not be parallel to the table top(front to rear).

Only thing I can come up with is shimming between the table and trunion.

How much 'error' are you observing at 45° tilt?(runout/inch or foot)

Lastly, are you SURE the miter gauge is accurate(square to the blade) and the miter slots parallel to the blade. I would verify those before even thinking about shimming the table/trunion. Is the table top perpendicular to the quill both side to side and front to rear in drill press position?

Unfortunately all these things interact!!!

If the table/trunion is not parallel, the 45 tilt and the drill press position should BOTH be be 'off' the same direction.

JPG,

You are correct in that all of those things need to be checked. I took the easy way out because I was under time constraints and needed to get the job done.

At 90 degrees the miter gauge is square to the blade. I have confirmed this many times and cross cuts at 90 are all fine. The error occurs when I tilt the table. I have not come up with a good way to measure the error using a dial indicator with the table at 45.

I will need to look into the problem when I have time and I'll post my findings.

[JPG]

JPG,

You are correct in that all of those things need to be checked. I took the easy way out because I was under time constraints and needed to get the job done.

At 90 degrees the miter gauge is square to the blade. I have confirmed this many times and cross cuts at 90 are all fine. The error occurs when I tilt the table. I have not come up with a good way to measure the error using a dial indicator with the table at 45.

I will need to look into the problem when I have time and I'll post my findings.

Do realize that checking by cutting boards does not guarantee 'squareness nor slot parallel to the blade. The kerf(and blade wobble) can cover up some small errors.

Using the 5/32 long wrench(straight one) with the miter gauge and a single blade tooth should work when the table is tilted as well as when it is horizontal. You should see that 1/16" runout if it is indeed the table. If not, the jig is suspect.

[dusty]

JPG,

You are correct in that all of those things need to be checked. I took the easy way out because I was under time constraints and needed to get the job done.

At 90 degrees the miter gauge is square to the blade. I have confirmed this many times and cross cuts at 90 are all fine. The error occurs when I tilt the table. I have not come up with a good way to measure the error using a dial indicator with the table at 45.

I will need to look into the problem when I have time and I'll post my findings.

Other than alignment, I do not believe that I have ever found a problem with the Mark V that "caused" an error in a cut. When I find something like a 1/16" discrepancy like you describe - I immediately suspect that I have caused it.

I am annal about alignment of the table and the fences but I am very likely to neglect locking the carriage and/or the headstock. Either of these left unlocked can/will introduce unwanted error.

It is really maddening when I find that I have done alignment only to find that the headstock was not locked. The headstock being loose is more likely to cause a vertical alignment issue rather than the lateral error that you describe BUT I recommend that you start there if you have not already done that.

The Bevel Sled, however, is a great idea even for a finely tuned Mark V.

[JPG]

. . .

The Bevel Sled, however, is a great idea even for a finely tuned Mark V.

Indeed! Got sorta sidetracked from that!:o

[tdubnik]

Other than alignment, I do not believe that I have ever found a problem with the Mark V that "caused" an error in a cut. When I find something like a 1/16" discrepancy like you describe - I immediately suspect that I have caused it.

I am annal about alignment of the table and the fences but I am very likely to neglect locking the carriage and/or the headstock. Either of these left unlocked can/will introduce unwanted error.

It is really maddening when I find that I have done alignment only to find that the headstock was not locked. The headstock being loose is more likely to cause a vertical alignment issue rather than the lateral error that you describe BUT I recommend that you start there if you have not already done that.

The Bevel Sled, however, is a great idea even for a finely tuned Mark V.

Dusty,

Everything was locked down so I know that is not the issue.

I do believe that I have an alingnment problem but I do not believe that it is a skewed table. I think that I have a vertical alignment problem with the main table. When the table is set at 90 degrees to the blade my table alignment is within .003 and my cuts are square. When I tilt the table the error occurs which would indicate to me that the table is not absolutely level with relation to the blade. I also notice some burning when doing bevel cuts.

I just have to find the time to analyze and correct this.