Minor Alignment Problem with Domino

[KevinW]

I am cutting dominos in rails to hold up a shelf.  Essentially I am cutting a mortise in the side of one board (shelf) and in the surface of another (rail).  This is not unlike the cuts shown for a draw on page 14 of the supplemental manual.  I am using the fence to set the position. When I assemble the boards the front of the rail is not flush with the side of the shelf. It is not off by much, less than 1/64 but more than 1/32.  I can compensate by adjusting the fence after I cut all the rails but I am at a loss to know what is causing the problem. I measured the mortises from the edge of the boards and they are off.  I also do not see any obvious operator error. I am also using the base support bracket when cutting the shelf. Any suggestions?

I assume I can use the fence in the way I am so the position will be the same.

 

[tjbnwi]

Do you have a pin fence or flag fence Domino?

Sounds like the pins or flags need to be adjusted. I have 2 Domino 500's one with each style fence. I adjusted the stops so the Dominos are totally interchangeable.

Tom

 

[KevinW]

If you mean the locating pins - they are flags.  But I retracted them so they are not the issue in themselves.

 

[Stone Message]

Hi Kevin

Dominos do have a little 'wiggle room' left and right and it is possible to adjust the lateral fit either with a mallet or more gently with a clamp. I do this quite often and they can take as much as 0.5 mm of movement depending on the hardness of the wood..

Peter

 

[tjbnwi]

If you mean the locating pins - they are flags.  But I retracted them so they are not the issue in themselves.

If you're not using the flags what are you referencing off of?

Tom

 

[fdengel]

Are you doing this sideways, with the long direction of the mortices running up and down, thus the distance from the "side" of the rail being an error in the distance between the fence and the slot (an error in a direction perpendicular to the fence), rather than an error along the length running parallel to the fence?

 

[KevinW]

I am referencing off the fence.  One cut is made with the board vertically - this in the face of the board.  The other is made with in clamped horizontally - the cut is made into the side of the board.  The two cuts are shown on page 14 of the supplemental manual and are I assume very common.  The issue is not play in the domino side to side - I cut on the middle setting so there is play laterally, but rather my problem is back to front.  Because I don't move the fence between cuts the boards should align, but they don't.  I can get near perfect alignment if I move the fence to take up the difference. The boards (poplar) are reasonably flat and square.

It would seem that boards should align better than they do.

 

[KevinW]

Are you doing this sideways, with the long direction of the mortices running up and down, thus the distance from the "side" of the rail being an error in the distance between the fence and the slot (an error in a direction perpendicular to the fence), rather than an error along the length running parallel to the fence?

If I understand your question you are asking if the problem is along the width of the mortise. It is not. I cut on the +6mm setting and there is sufficient play so there is no issue. The problem is what I would call the back/front direction.  (Now that I think about it I believe one of the mortises is a much tighter fit.) There is no room to adjust anything in the back/front direction. It seems despite the fact I am referencing off the fence the mortises are being cut in slightly different positions relative to the edge of the boards.

 

[tjbnwi]

Are you doing this sideways, with the long direction of the mortices running up and down, thus the distance from the "side" of the rail being an error in the distance between the fence and the slot (an error in a direction perpendicular to the fence), rather than an error along the length running parallel to the fence?

If I understand your question you are asking if the problem is along the width of the mortise. It is not. I cut on the +6mm setting and there is sufficient play so there is no issue. The problem is what I would call the back/front direction.  (Now that I think about it I believe one of the mortises is a much tighter fit.) There is no room to adjust anything in the back/front direction. It seems despite the fact I am referencing off the fence the mortises are being cut in slightly different positions relative to the edge of the boards.

It sounds like you are using the edge of the fence as a reference face. If this is the case I don't dought that the board edges do not line up. The edges of the fence are not machined edges.

In a previos post you stated the parts are off between 1/64" to 1/32" (0.0156 to 0.03125). A casting difference of 0.0075 to 0.016 will cause the parts to be off within your parameters. If you want to use the edge of the fence you will have to tweak each edge with a file so each edge is 0.0000" different from the centerline of the bit.

Tom

 

[Stoli]

Are you doing this sideways, with the long direction of the mortices running up and down, thus the distance from the "side" of the rail being an error in the distance between the fence and the slot (an error in a direction perpendicular to the fence), rather than an error along the length running parallel to the fence?

If I understand your question you are asking if the problem is along the width of the mortise. It is not. I cut on the +6mm setting and there is sufficient play so there is no issue. The problem is what I would call the back/front direction.  (Now that I think about it I believe one of the mortises is a much tighter fit.) There is no room to adjust anything in the back/front direction. It seems despite the fact I am referencing off the fence the mortises are being cut in slightly different positions relative to the edge of the boards.

It sounds like you are using the edge of the fence as a reference face. If this is the case I don't dought that the board edges do not line up. The edges of the fence are not machined edges.

In a previos post you stated the parts are off between 1/64" to 1/32" (0.0156 to 0.03125). A casting difference of 0.0075 to 0.016 will cause the parts to be off within your parameters. If you want to use the edge of the fence you will have to tweak each edge with a file so each edge is 0.0000" different from the centerline of the bit.

Tom

It sounds like you are having alignment problems along the SHORT dimension of the dominos, right?  If so, you will want to make sure that when you cut into the edge of the board that you are in fact referencing off of the fence.  In this configuration, it is actually easy to mistakenly be placing the domino flat on your bench so you are in effect referencing off the bottom of the domino and the bottom surface of the board.

 

[fdengel]

It sounds like you are having alignment problems along the SHORT dimension of the dominos, right?  If so, you will want to make sure that when you cut into the edge of the board that you are in fact referencing off of the fence.  In this configuration, it is actually easy to mistakenly be placing the domino flat on your bench so you are in effect referencing off the bottom of the domino and the bottom surface of the board.

Yeah, I did that once or twice too before I caught on...

It is also possible that if the edge of the wood that the fence is sitting against is not 100% flat, the fence could be on a high spot on the side, which may not be apparent when checking the position of the domino.

Also need to be careful that the fence is consistently against a pair of mating surfaces between the two pieces and isn't getting flipped around.

 

[KevinW]

Are you doing this sideways, with the long direction of the mortices running up and down, thus the distance from the "side" of the rail being an error in the distance between the fence and the slot (an error in a direction perpendicular to the fence), rather than an error along the length running parallel to the fence?

If I understand your question you are asking if the problem is along the width of the mortise. It is not. I cut on the +6mm setting and there is sufficient play so there is no issue. The problem is what I would call the back/front direction.  (Now that I think about it I believe one of the mortises is a much tighter fit.) There is no room to adjust anything in the back/front direction. It seems despite the fact I am referencing off the fence the mortises are being cut in slightly different positions relative to the edge of the boards.

It sounds like you are using the edge of the fence as a reference face. If this is the case I don't dought that the board edges do not line up. The edges of the fence are not machined edges.

In a previos post you stated the parts are off between 1/64" to 1/32" (0.0156 to 0.03125). A casting difference of 0.0075 to 0.016 will cause the parts to be off within your parameters. If you want to use the edge of the fence you will have to tweak each edge with a file so each edge is 0.0000" different from the centerline of the bit.

Tom

You are correct.  I am using the bottom of the fence to register the cuts.  From everything I have read and seen that is the way it is intended to be used. As to your suggestion you seem to be saying I need to file the edge of each board to compensate for the casting difference. I don't know that I would be able to easily get the 0.0 difference. I can eliminate the difference by making test cuts on scrap for the second piece. 

It is disappointing that fence is not sufficiently flat - if that is the case. It may be the case since the length of the board under the fence for each cut is significantly different.

Thanks for your suggestions

 

[tjbnwi]

I believe I am misunderstanding the issue. How about a couple of pictures?

Tom

 

[tjbnwi]

Are you trying to accomplish the assembly on page 17 of this manual?

http://www.waterfront-woods.com/festool/Domino_DF_500.pdf

The shelfs should line up on the lines, in this case the face is the reference surface.

I read your problem as the front edges not lining up. Is this the issue? If so you need to use the paddles to reference off the edges of the shelf and case side. For the paddles to work properly them must be exactly the same distance from the center line of the Domino.

Tom