Some of my recent endeavors have taught me how not to program toolpaths/cuts with the CNC module; several instances where the spindle was completely stopped by the stock and my A350 kept trying to follow the toolpath. I was usually pretty quick on the draw to pause/cancel and in one case power off.
The cumulative result of these errors has given me the following outcome on a 2D facing operation:
A FB group led me to the most likely culprit: that my spindle is no longer perpendicular to the bed.
Since this is my first CNC machine, and the SM is made in the manner it is, Iâm not sure of the best process to try to tram the spindle.
I realize it could several different issues (or a mix of them):
Perhaps the Y rail bracket is not level
Maybe the module plate on the X rail is askew
Maybe the spindle itself got slightly out of whack in the CNC module
Do any of you have recommendations or resources? Should I plan to remove the housing on the Module to affect realignment of the spindle?
I did order the newer rails when they were on sale (havenât arrived yet) so I donât know if those would simply solve the issue or if Iâm going to need to do some heavier calibration/adjustments.
As always, thanks in advance, this forum has been an amazing resource!
Is there play in your linear module brackets? Are they solid or do they rock either back and forth or left/right? Does the bed tilt easily if you press down on either end (more than natural deflection)?
Have you tried tramming the x-axis?
Do you have a square that you can check that the bit is perpendicular to your bed?
What type of bit (downcut or upcut)? How many flutes?
I have not attempted any solutions yet as the pics above are from a day or two ago (fortunately that was the back of the piece and the outcome is acceptable for it).
I will check the play on the other brackets and see but Iâm not certain what I would expect normal deflection vs just past normal to be. I have had a few plunge operations push the bed down farther than felt it should go but it didnât seem to affect other carves (or I was doing cut throughs and the difference didnât matter).
I do have a square but should I be measuring from the bit or from the spindle? I imagine different size bits might give me different levels of âoffâ (the 6.35 being the largest flat end I have, but going down to 1 mm bits).
I hope SM grants you Forum Sainthood soon SDJ, youâve earned it 10^10 times over!
Itâs the difference between being totally tight and where you feel like itâs moving freely and then hitting a stopping point - even if that difference is less than a millimeter. I think youâll know when itâs loose.
From the bit. Bit size doesnât really matter. Generally your larger bits are going to be longer so easier to tell.
SM would actually have to have a presence on here to do that. I did get a whole $10 coupon from Edmund once.
-S
Youâre correct that itâs a tramming issue. Youâve not, however, got a good diagnostic candidate in your head.
If you had a rotation around the Y-axis, youâd have a wedge of varying thickness spanning the X-axis.
This is the closest one, but not exact. See below.
Possible, though rather unlikely given how the spindle is mounted inside.
What seems most likely is that the milling head is not affixed to the X-axis rail with any precision. Itâs important to realize that thereâs quite a bit of slop in the way that the work heads bolt onto the mounting plates. Just loosen the bolts and wiggle it around to see for yourself. The rotation is in the X-Z plane, around the Y-axis. Assume, for the moment, that cutting tool is perpendicular in the Y-Z plane. When itâs not perpendicular in the X-Z plane, the bottom of the groove made with travel parallel to the Y-axis will be higher on one side than another. A sequence of grooves along the Y-axis, as youâve done, would have ridges where the high side of one groove meets the low side of another.
If youâre looking for smooth surface operation, youâll need to get your spindle mounted perpendicularly to the work surface. If youâre looking for a really smooth surface, youâll need a precision measuring device like a dial indicator. Tramming is well-discussed on the internet generally and has received some attention here.
Every time you mount the milling head, youâll have to check tram for the X-Z plane, because thatâs where the bulk of variation in mounting is. If youâre out of tram in the Y-Z plane, thatâs a rather more difficult thing to deal with.
Last comment: Parallel grooves along the X-axis will diminish the effect of being out of tram in the X-Z plane.
Iâve never had a problem with this on my machine and hasnât been the issue troubleshooting anyone on FB, but thatâs probably the case. I always let the head hang down in the bottom of the screw holes and tighten them all snug before I do a final tighten and that gets mine nice and straight. Check that this is the case with yours and then use a square to determine if the bit is perpendicular to the x-axis and that thereâs no play in the head. If thereâs no play and it isnât square, then you can loosen and adjust the head in the bracket. If there is play youâll need to adjust to remove it. (maybe contact support first)
If it was the x-axis needing tramming (assuming bit is perpendicular to x-axis) then you would still have nice even cuts, just would end up thinner on one side of workpiece.
So I finally had time to do a little more investigating. Below are the pictures I took with a level and square. Regarding the level bubble, I think the entire place the machine is sitting is a tad slanted, but it seems to be an equal slant.
Pressing on the platform with my finger the movement at the front of the platform seemed pretty minimal but there was more play at the back of the platform.
The square really illustrated the issue.
How should I go about adjusting it? Loosen the screws on the back of the module and see if I can get it square/more square before tightening? Or is it a possibility the bit in the collet didnât sit correctly? Other techniques?
Thanks again!
Eh9 - I did do some searching but nothing seemed to a helpful application to the snapmakers build vs other CNCâs mounting more of a dedicated router.
Itâs nearly impossible to insert the bit wrong. Itâs not like a drill chuck that you can get it off centered when itâs wide open. But when you do that you know immediately. Youâd definitely notice the vibrations. It could be badly machined, but it still wouldnât cause the issues youâre having since itâs spinning - the angle would be changing as its spun around.
Itâs hard to tell from pictures but it does look like youâre not perpendicular. Spin the bit as you look to check.
If you donât have play in the bracket then just loosen the mounting screws (assuming that youâve checked that the x-axis is parallel to the spoil board (search for tramming if you donât know how) If it isnât/you havenât then do that first), square it up and re-tighten slowly and in a couple steps each from just tight to fully tight. You can probably use the side of the module to check instead of the bit.
Thanks for the digital suggestion, I will definitely invest in that!
As for checking if the X axis is parallel, I did search and watch a few YT videos on Tramming before my original post and in one they used a 2 gauge device that mounted into the spindle (with a piece of glass resting on their bed). Is that the method youâd recommend to check? I will look into your thread after work (if the answer is there no need to reply).
It was after that video that I posted here just because the adjustments he made didnât seem possible on the Snapmaker based on how the modules attach.
You can adjust one rotation plane easily, the X-Z plane, by changing the position of the work head on the mounting flange of the X-axis linear module. The other one, the Y-Z, is only adjustable with difficult, as there are no built-in adjustments in the SM.
The easiest way to get the X-Z plane right is to fix the head in place before bolt tightening.
Mount a solid pin in the collet. 6.35 mm is exactly 1/4". A short length of drill rod is fine.
Clamp the pin to a square. Itâs best if the square has a V-groove for the pin to rest in. Something like a V-block would work (example non-affiliate link).
Rest the other side of the square on the build surface.
Post 33 in particular. Engineering blocks are the precise way. A couple cans are the low tech way. (If you use 3, you can check how consistent their dimensions are).
From the photos it looks like the x-z is the problem. And with deflection and the machines lack of rigidity in that direction, it ends up taking care of itself.
After taking my sweet time, I finally checked in on the solutions SDJ and EH proposed. Loosening the screws on the back of the module I had no idea there was that much play side to side (and think this was the culprit).
I did end up purchasing the digital level SDJ mentioned and the angle as mounted came to around 89.5. After holding the module while tightening that oscillated between 90-89.8 so definite improvement. I might try loosening again to see if I can get closer to 90 but if not it looks much much closer to my square as well.
Want to thank both of you for your comments. I gained some ancillary wisdom from the threads you linked and added a few new tools to the arsenal (the digital level and I have 123 blocks on the way - something I am surprised I never picked up before).
Iâm glad I didnât have the vertical play SDJ did (Iâve seen my module make that motion when one of the clamp screws was not low enough, but there isnât any play now).
