Hi all, i have a problem with cuts in the lower corners of the work area. Pictures show whats happened.
The area that seems to be the problem is around 200mm from the bottom and side. I set my work area 150mm on all sides to compensate for this but problem still catches me out some times.
(First picture is misleading as board is oversized but problem is around same distance inside work area that normally occurs)
Things i know:
1- my accuracy has a prominate sag on the vertical centre top that decreases the lower the sled moves down.
2- when these cuts mess up the longest chain to the ring is loose to the point the carriage has come off the ring in the past but not always.
3. My last calibration i did, had a shorter distance between motors as measured by the chains. 3001.64 down from 3008mm this improved the vertical sag from 9mm to around 3-4mm.
I have ready @madgrizzle post on accuracy and simulation. It would seem that my issue maybe motors thinking they are further apart then they actually are.
Can anyone please help about how i should proceed from here.
the fact that the chain is extremely slack is indicating that you have too much friction between your sled and the workpiece. a wider top beam could help a little bit, but you really need to address the friction issue.
problems at the center top could be a couple things. If your power supply is a bit weak, that could account for it. If the top beam is a bit low, that could account for it. you could also have calibration issues (including motor distance or rotation radius)
Thank you for the advice guys. I never considered friction to be an issue but certainly seems like the likely candidate. I have experienced this issue with both an mdf sled and now a acrylic sled. @Dustcloud recommended wax in a previous post so will definitely give that a try.
@dlang the power supply is the one that comes with the kit. My sled weights total of 8.8kg what are your thoughts? Upgrade power supply or decrease sled weight? Hmm maybe less weight less friction… possible 2 birds 1 stone
Thank you for the advice guys. I never considered friction to be an issue but certainly seems like the likely candidate. I have experienced this issue with both an mdf sled and now a acrylic sled. @Dustcloud recommended wax in a previous post so will definitely give that a try.
sand it really smooth and wax it.
double check your frame angle, if you have it tipped back too far it can cause
this
@dlang the power supply is the one that comes with the kit. My sled weights
total of 8.8kg what are your thoughts? Upgrade power supply or decrease sled
weight? Hmm maybe less weight less friction… possible 2 birds 1 stone
8.8Kg is in the right ballpark, too light and you have trouble drilling into the
material
less weight = less friction but also = less down force, so it’s probably not the
solution to your problems at the bottom.
we have had cases where the stock power supply strugged. Do you have a volt
meter you can put on it when you are moving the sled up near the top center? if
you see the voltage drop under those conditions, then you need a more powerful
supply (stock is 12v 4A, other 12v power supplies can be found readily, or if
you can get hold of a large 12v battery for testing…)
but your problems in the bottom corners are friction.
yeah, we did a combo of reducing friction, increasing weitght and slowing down. If possible you have to control where downcuts occur… but all of that is really workarounds. Lots of room to improve.
Like in all things being developed there needs to be a set of requirements/goals and anything below that is a problem. if the goal/requirement is to cut at 1cm/second then needing to slow to 1/10 that for regions is a bug (no consideration given to actual speeds used) and once we agree it’s a problem we can collectively work to resolve it (This is a community thing, not the responsiblity of a kit creator to fix). But we have to ackniowledge it as an issue to resolve.
in short, try the workarounds to get things done until you have time to contribute to improving the problem.
These voltmeters are cheap and easy to use and handy to just permanently connect to lower volt DC power supplies. I usually have some laying around, but if I go look right now the swamprats will have hidden them.
The following is a random eBay example. I searched for voltmeter, then sorted for lowest price and shipping.
Again thank you all for the advice I really appreciate your effort in responding. Im having a couple days break from the maslow now to tackle the veg garden before spring. I will definitely work through these suggestions early next week and post updates along the way.
Hey again, so the suggestion regarding the cuts in lower corners being friction related was on the money thank you everyone. I waxed the sledand added a curved edge to it. I also noticed that with the vacuum attached and on there is ( and this is obvious now ) suction between the sled and work material. So when cuts are in the risky places I now turn vacuum off briefly. Another thing im doing also is removing, when possible the frayed edges of the cut in the lower corners. Im not sure which one plays the biggest role but thats what ive been doing and its been successful.
I havent check motor voltage yet but plan to do that soon and will again post outcome
) suction between the sled and work material. So when cuts are in the risky places I now turn vacuum off briefly. Another thing im doing also is removing, when possible the frayed edges of the cut in the lower corners. Im not sure which one plays the biggest role but thats what ive been doing and its been successful.