Help! My simulation and what. Cut are different

would that pocket be a lot of extra cutting time ?

With the same depth of cut & feedrate it would be double the time.

With a shallower depth of cut you can also kick up the feedrate, so they almost cancel each other.

I can’t imagine that is an extremely long toolpath. So double the time but get a good cut.

3 Likes

OK now I think I understand what you’re saying you only cut that little pocket for the part of the bit touches the wood, but has no flutes. Is that correct?
Also .79 is it the most common size I’ve been cutting and thickness should I need to cut a pocket for that with the bits that come with the shapeoko?

The biggest reason is to relieve the stress/force on the cutter as it gets deeper in the slot.
Even if the flute is long enough, chips tend to bunch up in the slot, and greatly increase friction between the cutter & material. This creates heat, which you want to avoid. By taking 2 passes on each level, you create a small relief for the chips to escape, and reduce the ‘pinching’ on the tool.

Ideally, what you want to do is climb-cut the pass away from the vector first. The deflection in the tool will push it AWAY from the vector, making sure it’s leaving stock for the 2nd pass. Then climb cut the ‘finish’ pass along the vector, only removing the remaining material from the 1st pass.

These machines are ‘open loop’. The controller has no idea where the head/tool is. It only knows where it told the cutter to go. If the cutter somehow gets lost, makes a wrong turn, or gets held up (Lost Steps), the controller thinks it made it to the last point, and tells it to go to the next point.
You can make it lose steps if you put enough pressure on the head with your hands, or pull it off of it’s intended route.
If the force on the tool exceeds the force of the stepper motors to hold the tool in it’s intended position, it will go off course. These are not industrial grade steppers, so you have to go easy on them. :wink:

In your case, it looks like the path may have completed successfully if you had used tabs to hold the ‘plug’ (the part) in place during the final cut through the bottom of the material. Or use 2-way tape to hole the loose piece in place for the final cut.

4 Likes

Did you initialize the machine before doing it again? I’m new here so may not know what I’m talking about. Just a word of warning. lol!

I believe the machine reinitialize is every time I hit the big red button when I turn it back on.
Also, how deep are we talking? These cuts that are considered relief cuts? Are they all the way through the wood or just at the top where the flute stop?
Thanks again everyone for all this help I really appreciate it @Tod1d that relief cut question was for you.

Would this all need to happen for 3/4” hardwood?

All the way on every step down. Each step down is based on the DOC (Depth of Cut) setting for your operation. But it is just one “pocket” operation with the DOC set appropriately. The machine will calculate how many steps to make based on your DOC and total cutting depth (in this case to the bottom of the machine). If using tabs I believe the final pass (to cutout the tabs) is a separate (contour) operation.

Does that help clear it up?

Some yes, I would love to see this in action anyone know a video link?
Also, so if I want to just cut say the outline of a sign out of 3/4 hardwood you guys would make two separate cuts to go around the outside in this way were talking about above?

I wouldn’t think of it as 2 separate cuts. It’s just a pocket about 10% or so wider than your bit as opposed to a count our cut. Use the pocket operation.

Ahh ha!! Finally the :bulb:goes on for me thanks guys !!
I can’t thank you all enough for the support!

1 Like

This topic was automatically closed after 30 days. New replies are no longer allowed.