What am I doing incorrectly with this guide bushing?

[®smpr_fi_mac®]

This is the second Bosch RA1113 bushing that I've destroyed.  1/2" straight bit.  17/32" ID on the bushing.

I used the centering cone and *thought* the subbase was centered. 

Bit is apparently hitting the guide and tearing it off.  

Help?


Oh, here's the jig I'm using. Trying to cut mortices in the ends of a table top for floating tenons.

https://youtu.be/Bx1Mg2mTMO0

[greenacres2]

Might be as simple as tight clearances. A 1/32” total provides only 1/64” margin on a side. Doesn’t take much runout to cause interference. And it’s combined runout of bit, collet, bushing and faceplate. I’d try a little more difference between bit & bushing.
Earl

[KC]

This is the second Bosch RA1113 bushing that I've destroyed.  1/2" straight bit.  17/32" ID on the bushing.

I used the centering cone and *thought* the subbase was centered. 

Bit is apparently hitting the guide and tearing it off.  

Help?


Oh, here's the jig I'm using.  Trying to cut mortices in the ends of a table top for floating tenons.

https://youtu.be/Bx1Mg2mTMO0

Is that a DeWalt 621?  If so, mine is off center just a wee bit.  Supplemental bases (two from Pat Warner and one from Amazon) are also off.  

For whatever that may be worth.

[®smpr_fi_mac®]

Okay, cool.

Looks like I'll have to use the larger OD/ID bushing to hog out the waste and then go back and clear it the final 1/16" with a chisel.  Slow, but feasible. 

KC, it's a Bosch MR23EVS.

[OneStaple]

I agree on the too little clearance assessment. Also, any torque you put on the bushing while routing might be enough to use up that 1/64" clearance (max, if everything is aligned perfectly) and create contact.

Tyler

[Willyou]

I don't disagree with the above clearance comments. And this is just a opinion based on looking at pictures. So, I could be way off base. The Bosch guide bushing appears to be made with the bushing cylinder swedged into a flat plate. It looks like the swedged end has pulled loose from the plate. It could be caused by contact with the cutter. I don't know. But, it seems to me, that method of manufacture leaves possibilities of bending, flexing, loosening, etc. I like the Porter Cable guide bushings which are machined from a solid piece of steel or brass. You could use these, but you will probably have to also change the plastic base plate. This is not a big deal; easy to make from 1/4" acrylic.

[®smpr_fi_mac®]

I agree on the too little clearance assessment. Also, any torque you put on the bushing while routing might be enough to use up that 1/64" clearance (max, if everything is aligned perfectly) and create contact.

Tyler

Yeah, I agree, too. Lesson learned!

I don't disagree with the above clearance comments. And this is just a opinion based on looking at pictures. So, I could be way off base. The Bosch guide bushing appears to be made with the bushing cylinder swedged into a flat plate. It looks like the swedged end has pulled loose from the plate. It could be caused by contact with the cutter. I don't know. But, it seems to me, that method of manufacture leaves possibilities of bending, flexing, loosening, etc. I like the Porter Cable guide bushings which are machined from a solid piece of steel or brass. You could use these, but you will probably have to also change the plastic base plate. This is not a big deal; easy to make from 1/4" acrylic.

This was mentioned by a friend of mine. After this project is done I'll buy the PC bushings.

Yeah, the guide is swedged to the plate.

[jteneyck]

This is the second Bosch RA1113 bushing that I've destroyed.  1/2" straight bit.  17/32" ID on the bushing.

I used the centering cone and *thought* the subbase was centered. 

Bit is apparently hitting the guide and tearing it off.  

Help?


Oh, here's the jig I'm using.  Trying to cut mortices in the ends of a table top for floating tenons.

https://youtu.be/Bx1Mg2mTMO

Nevermind.  Can't seem to delete this.  

John