I could use some help tramming my machine. I took my time while building it and I got just about dead square. I’m 43 3/4in corner to corner (within the width of the line on the tape measure). But it’s way out of tram… I put on the tramming jig and it looks to be off by nearly 1/16" over the 7" swing. I’ve got no play in the core and the mounts are all tight. All the bearings in the core touch and rotate with the Z rods.
If I center the router in the machine with the origin at the near left side, let’s call that 0 degrees. That makes Xmax, Ymin (near right) 90 degress, Xmax,Ymax (back right) 180 degrees and Xmin,Ymax (back left) 270 degrees.
What I measure is that the 270 degree position is the low spot. 0 degrees is .8mm high, 90 degrees is 1.4mm high and 180 degrees is .8mm high.
First off that is pretty good, I doubt you would notice any scalloping with an 1/8" .
Is that left side (the starting point of your vid) the lowest? If that is the case you need to move the top of the router away from that point. I would try loosening the other side of the clamp and tightening that side. see if that gets it any closer. (you can also do the opposite with the bottom, loosen that side and tighten the other).
I think side to side is a tightening thing, front to back is where shimming can come in.
Are you noticing a problem or you just trying to achieve perfection? I think what you have would be pretty solid for most projects.
If you have not surfaced your spoil board, there are ways you can get bogus tram readings. Screwing down the spoil board can warp it a bit, the MDF of your rig can conform to bumps and depressions in the bench beneath. There may be inconsistent manufacturing of the MDF, and the leg lengths you are using may not be creating a plane perfectly parallel to your spoil board. Take a couple of scrap boards. Run one the length of your machine and then surface the board with passes parallel to the length of your machine at slow speed (to mitigate deflection issues), shallow DOC, and your widest flat bit. Do the same with the second board only mounting the board running the width and with passes running parallel to the width. Take a look at the result and see how much scalloping you have. Also notice if the depth of the cut varies.
1/16" over 7" is about a half degree. One end of a flat bottom 1/8" bit will be 0.001" lower than the center. Tolerances are all relative, but that seems pretty good.
If the distances between the clamps was 3.5", then to remove a 1/16" error, you would put a 1/32" shim or so. Of course just taking it apart and putting it back together might change it by that much.
I’ve done a few things already, but none that this would make a difference with. However, I’m wanting to get into some inlays eventually. And since you are working upside down and backwards for the male part, any error is effectively doubled. So I’m more trying to head off future problems than current issues. I’m not really chasing perfection per se, so much as trying to not be lazy about my setup. If I can spend 15 minutes on an easy improvement, why not?
The table surface the machine is mounted on was a leftover piece of cheap 3/4 plywood from HD and had a slight bow to it. I ran a couple projects on it where that bow wouldn’t matter, but I want to try a V-Carve soon and that’s going to be a big deal. So I’ve screwed down the spoil board (3/4 MDF) now and surfaced with a 5/8th router bit using a 45% stepover and noticed scalloping. I like your idea about using some scrap and checking how bad the scalloping is based on left-right vs front-back.
Fair enough. Hadn’t thought about how little that would be across a small bit. Just trying to avoid any visible lines in the top surface of a workpiece. But if the deviation is small enough, a light sanding will probably be able to take that out.
I don’t want to discourage you from working on it. I just want to make you feel confident that you can ignore if you’d like.
Stepover on pockets is going to remove any leading edges too, and there will be some error just from the forces in cutting moving the bit up and down a little. IDK how much, but 0.001" seems pretty possible to me.
You can do what makes you happy though. Shim it or not, I think you’re going to have a great machine.
I do feel better that I don’t have as big an issue as I originally thought. I’m very new to this and I was afraid I’d be screwing myself over for not taking a little extra time to make sure everything was squared up. I’ll probably try Ryan’s suggestion just with tightening and loosing some screws on the clamps, since that’s an easy thing to do, but I won’t obsess over it.
This is what we needed to hear. You understand why to do it and that for things you have already done it was not necessary. Sometimes I get this way, If I know it is not as perfect as I would like I spend some time getting it that way.
Try messing with the clamps first, then you can add a few layers of tape as a shim if needed. Heck like Heffe says try taking it out, adjust the clamps a bit and put it back in and see it is changes. Maybe there is some elephants foot or other wonky things on the clamp prints that might move it a bit. Small error means small solutions that are hard to find.
So, I messed with the clamps today. Loosened the top right, then tightened the top left all the way, then snugged up the top right again. Did the opposite on the bottom clamp. A .021 feeler gauge just barely touches the screw in the jig on the high side now. That’s a helluva lot better than it was. Thanks much!
One (pretty academical) thought: The printed feet parts are open below, letting the tubes sit on the base board, more or less. And that can (!!!) be a point - if you choose a pretty soft wood for your table construction, the tubes can sink in over the time, depending on their usage, the clamping force on the feet, ion storms, weather etc. The contact area of the lower margin of the tubes is pretty small. Should be no problem on hard phenolic resin coated plywood (in Germany it is sold as “Siebdruckplatte”). The drawback: The surface of those is more like hills and valleys, and leveling it is a mess.
So, I thought about putting a piece of flat metal under the tubes to give them a more defined rest - but did not do so yet. Glueing a large washer between the tube and the desk would be an option. YMMV.
At least it is a good practice to make sure the tubes sit firmly on the desk / frame surface before tightening the feet’s clamping screws.
