I was originally using the engrave toolpath so that the cut would be right on the center of the line. The toolpaths start option was not available for that. Once I switched over to the part toolpath I was able to adjust the start.
Things seem to be cutting well again!
Is there any way to have set the cam to overcut the path?
Sometimes the drag knife doesn’t cut all of the way through and leaves a snag where the end of the cut meets the start. It would be nice to be able to recut the start of the path for about 1 cm before moving on to the next part.
You should be able to do a second toolpatht right on top.
I was hoping for a global setting that would keep me from the need to draw tiny overcut paths on about 400 different toolpaths that already have cam. I’ll keep that option in mind though, Thanks!
Yikes, Didn’t think about that. if any of them are duplicates you can set up the toolpaths and cut, paste and even rotate or pattern them.
Yes, they are mostly duplicates but it is quite an undertaking to tile, rotate, Set start point tile again and then set the cut order for a sheet of 70 duplicates. I just worked through the 9 current jobs yesterday and it took several hours to get them all reworked with the addition of a start point.
It’s just a minor annoyance at this point with the interrupted cut so I’ll just keep going as is for now. Thanks as always!
Dan
I only really briefly watched your video, but how does the vacuum table work? the groves are at the bottom and it still sucks it?
The channels are inside the two layers. The bottom layer is made from hardboard and the sides are painted so the vacuum only gets pulled through the top layer of the MDF.
Where can I get a 20T pulley or larger 
that is compatible? Do you carry them in the shop? How do I change the firmware to account for the new ratio? Thanks!
Of course the question is why do you want the larger pulleys? The machine is limited in firmware for maximum speed, and is actually capable of much higher. If you already have the 16T ones, what advantage do you expect from changing them?
20T pulleys are common elsewhere, but I haven’t seen them in the V1 shop. They should be easy enough to source.
The firmware will need to know the new resolution. Depending on your board and stepper drivers:
Currently, it is:
200 full steps/revolution * 32X microstepping (DRV8825) / (16 teeth * 2mm) = 200 steps/mm
You would change that to:
200 full steps/revolution * 32X microstepping (DRV8825) / (20 teeth * 2mm) = 160 steps/mm
If your microstepping is set to 16X (I think the SKR boards do this) those numbers are halved.
The steps/mm can be adjusted in Marlin via the LCD, or you could recompile the firmware by changing the line in configuration.h. Be sure to save the changes if you do it via LCD.
Thanks Dan for your reply!
If you scroll up to around Jan 16th in this thread I started this conversation and it was Ryan’s suggestion to go to more teeth. I do realize that the software limit can be overridden and as you suggest that would be the easiest option. I got worried I’d loose too much torque by the comments I was getting but I could just see what happens.
After an afternoon of adjusting the max velocity, I have settled on 100 mm/s for both X and Y and left the Z-axis at 50 mm/s. Any faster than that and I got skipped steps.
I would love to get the machine cutting faster but I believe getting a pulley with more teeth or some other major upgrade is going to be necessary. It was a hot day in the shop but the steppers never got over 55C. Acceleration settings and small details in the cut kept me from going max speed all the time but I am very happy to be cutting considerable faster! Thanks everyone!
More teeth on the pulley reduces the max torque. You can increase the max torque with the same number of teeth by increasing driver voltage. Running at 24V will increase the available speed by being able to overcome the induced back voltage from the steppers. This might be a more worthwhile improvement.
Agree. At those speeds larger pulleys and higher pitch leadscrews would benefit you. The tiny amount of torque you have available at 100mm/s is tiny.
20% larger diameter = 20% higher speed…20% less torque.
But you really need to balance it, if you go 20% bigger and 20% faster you still barely have any torque to spare. You might want to go larger. I am set for really good power at 15mm/s after that it drops off fast. look up the torque curve for whatever steppers you have.
24v will also help with faster RPMS like Dan pointed out. I suggest doing both.
Does this power supply look like it would work with my mini rambo?
You don’t even need a full Amp. I can send you one Tuesday if you can wait, if not anything more that 0.5A should work fine.
I’m not in any hurry, send me a link to the store and I can order it or I’ll just send you some funds.
We have a vacuum table very similar to this on the ShopBot at work and it has enough suction to hold aluminum plate while it’s being machined. For critical stuff, we’ll augment with the masking tape / CA glue trick and it’s rock solid. It really is incredible just how well this method works.
Newbie getting ready to build a lowrider. Regarding the skipping steps issue, has anyone experimented with 15mm belts instead of the 10mm ones? That’s one upgrade I’m considering for my build to avoid skipped steps and belt stretch.
Have you looked at adjusting the travel speeds?