Catch All Tray Question

[Rob302]

Everything looks great in Vectric. When I actually cut it out there is a tiny lip left at the bottom.

I have tried using 2 different bits for clearing and then the bowl bit to round the bottom. The only time it is smooth is if I use the bowl bit the entire time.

Any suggestions??

[TReischl]

How are you setting Z when changing bits? Piece of paper? Electronically?

Do you use the same spot on the board for all tool Z height touch offs? I don't care how flat we think the board is, moving to a different location for each tool is a mistake.

[Rob302]

Hello, I use the touch off puck that came with my Axiom. I always use the lower-left corner to set Z-Axis. But this has happened on 3 different workpieces.

[JoeBlow]

That's a fairly substantial lip. A couple years ago I ran a test with the included touch off puck that came with my Axiom machine....

placed puck on machine bed
used a .25BN
utilized tool touch off function on the HHC
after touch off my safe Z was set to move to 75mm
I then returned Z to the uppermost limit and jotted that number down from the HHC
repeated 10 times in same location with same process

Compared my results and there was a fairly large difference.

Did same test using a piece of paper for setting Z. All 10 results were equal.

Perhaps a hillbilly test but I never used the puck again after that. The paper method is much more accurate in my opinion. I'm always careful how I use tool changes, preferring to keep the same tool throughout the final finish milling to prevent this from happening in the first place. When circumstances do require a tool change, I will set Z a smidge higher and cheat my way back down as needed.

Otherwise, what TReischi said about using the exact same location for each tool change is a must.

[Adrian]

Thing with pucks is it's all about the response time of the software to the signal. The touch off plate (same thing) I use on my Shopbot is excellent and gives 100% results all the time even though their control software is quite primitive in many ways.

I've helped out people with other machines and theirs are all over the place. Slowing down the speed the Z moves at when approaching the touch off device can help.

Another thing to bear in mind with machines that have a bit of flex in them is that cutting with a bowl bit is going put more upwards pressure on the Z axis than using an endmill designed to cut on the bottom. The lip looks too big to be that issue but it's something to consider.

[martin54]

How are you preparing your stock? If you are using a thicknesser then it may be that you have a bit of snipe which would make the corner of your stock slightly lower than the rest
As Adrian has already suggested slowing down the z axis as it aproaches the touch plate can make a difference.

[gkas]

That's a fairly substantial lip. A couple years ago I ran a test with the included touch off puck that came with my Axiom machine....

placed puck on machine bed
used a .25BN
utilized tool touch off function on the HHC
after touch off my safe Z was set to move to 75mm
I then returned Z to the uppermost limit and jotted that number down from the HHC
repeated 10 times in same location with same process

Compared my results and there was a fairly large difference.

Did same test using a piece of paper for setting Z. All 10 results were equal.

Perhaps a hillbilly test but I never used the puck again after that. The paper method is much more accurate in my opinion. I'm always careful how I use tool changes, preferring to keep the same tool throughout the final finish milling to prevent this from happening in the first place. When circumstances do require a tool change, I will set Z a smidge higher and cheat my way back down as needed.

Otherwise, what TReischi said about using the exact same location for each tool change is a must.

Your puck will give much better readings if you check the following:

Check the puck thickness with an accurate caliper.

Compare the puck thickness with the actual controller setting in CAD THICKNESS. Mine was not very close. After I changed mine, I checked the Z0 so that I could not slide a thin piece of paper under it.

SLOW the TOOLSET SPEED down. I have mine lowered to 150.0. It may be slow, but I lower the Z with the bit BESIDE the puck. I can do this at full Z speed. Then I move the bit over the puck and hit TOOL SET. It's all very fast, but gentle on the puck/bit. No problem with accurate settings with even a 1/32 bit (0.03125").

After I made these changes, I've found the puck to be very reliable.

[JoeBlow]

Thanks for that info. I will re-visit the touch off puck settings and give it a try again. Some jobs that would be handy.