[mlk1950]

Just did a couple of test carves on my new home built machine. What would be the most likely thing or things to look at, that would cause this?

1/2 and 3/8 x 10 single start screws
Dumpster leadnuts
305oz. steppers
Mach3
1/4 stepped

Thanks Mike

[vger]

Z Axis, Missing steps? Loose coupling on screw? Can you post a pick of your Z axis?

[mrgraphic]

Could be loose set screw on spud shaft to belt drive gear. Use locktite

[mlk1950]

I just noticed a slight amount of play on the carriage to gantry. Will tighten that up and see.
If it is loosing steps on the Z, do I need to back off the Accel or the Velocity to remedy that?.

Got to go to work, be back later. Got to make some money so I can feed my CNC obsession.

Thanks Mike

[mlk1950]

Haven't had a chance to retest my machine yet, but I do have another question. Should the velocity and accel in Mach3 be set the same in all 3 axis? Or is it common to set them up different for each axis? Just trying to learn as much as I can about this.

Thank's Mike

[crane550]

Set your velocity up to suit the needs of each individual axis. You wouldn't limit the speed of each axis to the speed of your slowest axis would you?

I take it you just got your machine going. You WILL run into problems like this at first. I did do. My first few cuts looked TERRIBLE. I was certain this whole CNC thing was a mistake, and I had just wasted a lot of money. But keep at it, ask questions, and you will get it going, and you will be amazed at what a machine like this can do.

Do you have a build thread? Would love to see it.

Looks like a Solsylva? Check out my thread, I did a lot of upgrades to the original Solsylva design. I will be more then happy to give you G-code for better bearing blocks and such.

Alex
http://www.cnczone.com/forums/diy-cn...a_build_w.html

[mlk1950]

Set your velocity up to suit the needs of each individual axis. You wouldn't limit the speed of each axis to the speed of your slowest axis would you?

I take it you just got your machine going. You WILL run into problems like this at first. I did do. My first few cuts looked TERRIBLE. I was certain this whole CNC thing was a mistake, and I had just wasted a lot of money. But keep at it, ask questions, and you will get it going, and you will be amazed at what a machine like this can do.

Do you have a build thread? Would love to see it.

Looks like a Solsylva? Check out my thread, I did a lot of upgrades to the original Solsylva design. I will be more then happy to give you G-code for better bearing blocks and such.

Alex
http://www.cnczone.com/forums/diy-cn...a_build_w.html

Yes it is a Solsylva. It's been quite the experience, and loved every minute of it. I'm running the HCNC pro board with the 305 steppers. Here's a couple more pics. I'll welcome any suggestions or critiques you have to offer.

Thank's Mike

[vger]

Mike,

Looks pretty good Mine started in the garage too... then built a workshop in the back yard (12' X 20') to put it and my other stuff in cause my wife thinks the garage should be for cars....

I set my X and Y for max of 60 IPM and the Z at a max of 20 IPM. I have a 4th axis (rotary) that can be set in the A, B or C axis that is set at 1200 degrees per min (20 deg sec) to do turnings with.

One of my earlier projects was a full set of alpabet blocks for the grandson. They are 2" cubes of hard maple with the letters and numbers all raised like the standard old blocks. I attached a zip with all the files for them if you want. Use a 1/8" dia bit with the Z zeroed at the top surface, and the X & Y Zeroed at the lower left of the block.

Steve

PS, cut the letters in the end grain of the wood.

[mlk1950]

Thanks vger, maybe that's part of my problem. I'm running my Z at 40IPM, I'll try to slow that down and see if that helps. I went over and was reading Crane's thread and what I decided to use on my X rail and gantry supports was 1 3/4" poplar. It's in between oak and pine for hardness and stability. A friend has a cabinet shop and we ran them through the thickness planer and joiner as to make sure they were absolutely straight. So far they have worked very well. Now just have to learn as much as I can and get her fine tuned.

[crane550]

My first son was just born this last December. He will be able to start playing with blocks soon, looks like I got a new project!

[mlk1950]

I'm running mine fairly slow. The max I've ran it at was 40 IPM. What do you think a safe speed would be to shoot for. I'm planning on putting dampners and limit switches on in the future, cuz I'm only running the single start 10 acmes. Eventually I plan on upgrading to 8-2 starts.

[crane550]

I am running 1/2-10 single start right now. My X is running 55 and Y at 60. I could probably push it more but I have not yet. I only been running the ACME rods for a few days. I managed to cut mahogany today at those speeds using a 1/2 bit taking .175 per pass. Worked flawlessly.

I have 1/2-10 5 start on the way for the Y. My Z is currently using 1/2-8 2 start, which will retract the router at 160 with no problems. Could probably go faster, but it's hard to jog and zero much faster then that.

Are you running anything else electronics wise on your machine other then the Pro board? Limit switches, and E-stop are still on the to do list.

Also, I am curious about the photo with the jumpers running on your board. Did you modify your driver?

[mlk1950]

I am running 1/2-10 single start right now. My X is running 55 and Y at 60. I could probably push it more but I have not yet. I only been running the ACME rods for a few days. I managed to cut mahogany today at those speeds using a 1/2 bit taking .175 per pass. Worked flawlessly.

I have 1/2-10 5 start on the way for the Y. My Z is currently using 1/2-8 2 start, which will retract the router at 160 with no problems. Could probably go faster, but it's hard to jog and zero much faster then that.

Are you running anything else electronics wise on your machine other then the Pro board? Limit switches, and E-stop are still on the to do list.

Also, I am curious about the photo with the jumpers running on your board. Did you modify your driver?

No, just the pro board. The jumpers are a modification to bypass the 10 second idle current reduction built into the pro board. If the steppers sit idle for 10 seconds or more the current is reduced by I think 50%,and when I would try to jog, the steppers would stall. I had the biggest stalling problem on the X axis. Also I'm running the A-axis slaved on the X, cause I didn't want to run long belts on the X. So I bought the 4-axis pro board.
Here's a link for the mod: http://www.cnczone.com/forums/joes_c...-_mach3-3.html

Thanks Mike

[mlk1950]

I just noticed a slight amount of play on the carriage to gantry. Will tighten that up and see.
If it is loosing steps on the Z, do I need to back off the Accel or the Velocity to remedy that?.

Got to go to work, be back later. Got to make some money so I can feed my CNC obsession.

Thanks Mike

Ok, I tightened up the carriage to the gantry and it seemed help some, but still have some uneven cut on some letters. I was wondering if having the exact stop checked could have something to do with it. I noticed when it changes direction it has a bit of a jolt to it. Is there a setting in the mach to smooth that out? I still haven't tried slowing my Z down yet. Will try that tomorrow. Should I be using CV with settings turned off?

[jsheerin]

Enable constant velocity instead of exact stop (config, general config, right in the middle). There's a pdf tutorial on the settings on the mach website.

[mlk1950]

Sorry, I was wrong. The CV mode is on, but the distance and feed rate are turned off.

[crane550]

I would not enable CV. Set your acceleration speed down a bit (say to .25 seconds) and your IPM to 30 ballpark. Then slowly increase your speed and acceleration.

There are only a few things that will cause this, and all of them fairly easy to detect.

First, with your steppers OFF, spin your axis's by hand. You should be able to move them fairly easy with your fingers. If it is hard to spin your screws by hand you have a mechanical problem. Possibly alignment. Also, check for consistent resistance the entire run on your guide.

Also, spin them back and forth and see if there is any "slop", or "backlash", where the axis catches and starts to move in the opposite direction. Then you can go from there.

You should not need any Mach compensation to get this working well for you. This is definitely the hard part, but keep at it. You will get it.

How much trouble would posting a video of your problems be? That should make things a LOT easier to diagnose.

Alex

[vger]

Hey Mike,

I was looking again at the pictures in your first post. Is it at all possible that the upper and lower plates attached to the Z assembly are rolling or rocking when the Z changes direction? Try putting a level on the top plate (front to back) and run the Z up and down a few times and see if it changes angle.

Crane,

The blocks came out pretty nice. Made a little wheeled wagon 3 blocks wide, 6 blocks long, and 2 blocks deep that he carts them around in. You can test one of the letters on a piece of scrap. Just zero the bit (Z) to the top of the work piece.

Steve

[mlk1950]

I made a video on the first carve, but I wasn't real steady with the camera. Trying do do too many things at once. I'll post that one and then make a short one tonight with the camera mounted on a tripod.

Thanks Mike

[nomedia="http://www.youtube.com/watch?v=-AiK_IzBEmw"]YouTube - CNC first Carve[/nomedia]

[louieatienza]

Mike nice build... I also built a Solsylva router, though the 25 x 36 (I modified it to 25 x 32). Takes a little time to dial it in, as you'll have to readjust things periodically. Also now that you got it up and running, making more accurate parts is cake!

As for your problem; I'd just double check everything to make sure there's no excessive flex. It is a balancing act to find the happy medium between no flex and too tight, and very loose and a lot of slop. Spindle power is an issue too, where a higher powered one will "cut through" what's in its way and one with not enough power may just "bounce" on the wood. I had a similar problem too with v-carving, my workaround was to make two paths, one with the depth half the width of my font, and the second pass the full depth. VCarve will cut the full depth otherwise, and your router may not handle it especially is your fonts are wide.

I would try using basswood or alder for machining; it's very even grained and machines well with the router... and not too expensive to boot! Poplar cuts well, but may not be the best choice for clear...