Breaking homing switches - Uh, and lot's of other stuff

Sounds great. Now to do some carving!

I think that if you have hard limits set you will have to find a way to move it off the tripped switch to prevent re-occurring trips. I have no way of testing this though.

OK, sounds like maybe the filter is a way to go. I do hope someone (maybe me) will try the shielded twisted wire. I’m assuming (from what i’ve read from others) that the shield should be grounded only @ the gShield end?
i have lotsa caps & resistors @ home so i’m eager to set his up in a test mode.
i do have a question… and i’ll refer you to the discussion titled: “First Run Project - Stair Stepping” in which James Mitchell is attempting to run a 2 step carve using a 1/4" bit for rough cut and then 1/8th" for the finish work. his problem was stopping in the middle of the project, changing the bit, and then restarting with trying to 0,0 his work at the previous 0,0 spot. suggestions mentioned not moving the router between bit changes, but Mitchell responded (and i believe him) that changing bits on his Dewalt router while not moving the X or Y axis’ was very hit 'n miss, mostly miss. and therefore the 0,0 would be changed. would this be a good case for the limit switches being used? and when i say limit switches, i mean the homing switches. I’m new to this; I’ve just completed my 500mm machine & i’m in the final throws of setup (homing switches are not working, yet).
are the “homing” switches accurate enough so that when one would LIKE to do a 2 step project, using the “homing” switches would be accurate enough?

Russ from Coral Springs, FL.

@RussellHolt

I have the shielded wire setup. See below.

My homing switch setup is very accurate and repeatable. One of the functions that makes homing nice is tool changes.

Copied from one of my earlier posts:

Some suggestions:

  1. use shielded wire for the homing/limit switches. Leave the shield un-connected at the switch end, ground the shield at the controller end.
    2)for the wire that runs to the spindle (300W unit from Inventables), use shielded wire in the drag chain, twist the wires coming from the spindle to make a twisted pair, if you still have noise put a 0.1 ufd capacitor with the appropriate voltage rating across the spindle motor leads (close to the motor). Ground the shield on the spindle shielded wiring at the controller end.
  2. for the most benefit with the least problems configure grbl to use homing and soft limits (not hard limits). By the way, this really works (haven’t tried it with Easel - your mileage may vary).
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@RussellHolt

his problem was stopping in the middle of the project, changing the bit, and then restarting with trying to 0,0 his work at the previous 0,0 spot

Too many variables for a simple answer, but if you set things up properly and have your software set right — homing your machine prior to starting your carve can make this a simple process.

If your tool chain is set up right then you would only have to change two things with a tool change: 1) the mill and 2) you would need to reset Z = 0 unless you have a method to insure that the new tool was mounted with the tip exactly the same place as the previous tool.

Russell Holt, don’t know if you saw my latest response but I have solved my bit change problem. On easel when you go from rough carve to finish carve, over on the bottom right are two tabs labeled ‘lock motor’ and ‘unlock motor’. By applying ‘lock motor’ then change your Colette and bit then apply ‘unlock motor’ and go about your finish carve.

James,
I did catch that - i was very interested to see what the outcome would be.
I’m still skeptical about homing to 0,0 after the tool change
and this goes out to all who are following here:
Take the example of a rough cut and the finish cut using the same shank diameters, but different cutting diameter bits. If the 1st bit had a bite of 1/2" for rough cut and the 2nd bit had like 1/8 diameter cutting diameter, would using the same path work? Wouldn’t the X-Carve take the exact same path (if the bits’ shanks were both the same size) and therefore be off in the 2nd cut?
I say this 'cause when going through the Machine setup on the X-Carve it only asks about the bit shank size. (or do I have that wrong?).

Russ from Coral Springs, FL.

Russ, you didn’t mention which CAM program you’re using, but context would suggest it’s Easel.

I don’t use Easel so my comment may not apply.

My CAM program knows the details of the bit geometry that I select for each tool in my design, so the CAM program takes care of the details. All I have to do is set Work zero and run the G-code.

Darn, i thought I had replied to this.
Angus & Larry - I AM using Easel for the time being.
And I finally gained enough courage to do my 1st carve on plywood last night.
The X-Carve worked wonderfully - my securing the plywood to the wasteboard, not so good…
BUTT <-- the big but,
It was a test run, the wood was scrap, no bits were broken, I was ready to shut things down when they started going wrong. Very good learning run, and I’m chompin @ the bit (pun intended) for More CARVING!
tonight i screw down my plywood into the 2ndary wasteboard in order to carve out my clamps so i can use them for my projects.

I’d like to ask, since you all are seasoned on cnc, How do you work the waste-board thing? especially when you want to cut out pieces as opposed to creating inlay paths and whatever… do you just have a lot of cuts into the wasteboard? or do you have something in place like a 1/16" “buffer” sheet on top of the waste board that the bit is allowed to cut into? but what do you do about the X-Carve’s Waste Board’s clamp sockets?
don’t want to start a whole topic on this, 'cause maybe it’s a simple answer.

Russ

I put down a “Sacrifice Sheet” between the waste board and the work piece.
(I my case I am using some peg board I had laying around.)

Technically that is what the waste board is for but I do not want to go through the effort of replacing it regularly.

Pegboard - i like it, lotsa holes already. do you use the holes in the pegboard with clamps whose screws go thru the pegboard into the X-Carves Wasteboard threads?

Yep. My waste board is metric and the pegboard inch so only every 3rd set of holes lines up. But it has been working so far.

Thanks, Angus - i forgot to mention that pegboard is quite soft & therefore another good choice for a sacrificial medium.
but, still my question is how do you clamp your real workpiece to the pegboard?

Russ

I just clamp on top of the material.
One side of the peg bard flush with my material.
The other side I clamp on top of the material running the screw through a peg hole into the waist board thread.
That seems to be enough to keep everything in place.

THANKS, I understand, now.
so, you have gone & purchased longer screws for clamps, i’m guessing?

Russ

Russell, I assume that when you select your bit size for the second cut, easel uses that information to set up the difference in size.

I’m in the experimental tests w/my X-Carve, I’ll set up a couple of test for bit changes. thanks for the info.

Russ

@RussellHolt - I kinda use a combination of either a 3mm sacrificial sheet (MDF or similar), or I just let the work cut into the waste-board - after all, that’s what it’s there for.

For rough & ready jobs, I use an old bit of something to avoid cutting through the job.

For more accurate stuff however (like wooden clock gears), I clamp directly to the table surface, check for parallel with a dial indicator & then set the depth of cut to be around .75mm deeper than the job thickness. This allows for a full depth cut so everything is fully released (excepting any Tabs I’ve set), but not so deep that the tool will cut into my T-Slot channels or the threaded bolt holes. The less bits of stuff I have between the table (which was machined flat by the machine itself) and the job, generally introduces less opportunity for error - again, this is not an issue if Z axis accuracy isn’t critical.

With regards to cutting plywood - I love the stuff. It’s strong, it’s generally pretty flat, and if it’s reasonable quality, it cleans up really well. Yes, the edges can be ugly, but they can be filled and polished and made into a feature, or they can be veneered to match the surface. Nice ply is relatively cheap (compared to good timber, anyway) and with a little care, a sheet can last a long time.

My wasteboard, now has so many cuts in it, I’m either going to do a 2mm surface clean-up, or I’m going to sell it as abstract art…

Well, I’ve been kicking the idea around a bit, and think that maybe a daughter shield between the arduino and grbl boards might be worthwhile. I am thinking it will install between the two we currently have, and bring the missing signal lines out to standard wire connectors such as Brian used, with filtering on board for the noise issues. Also thinking of including ability for PWM on 48V spindles, as well as a 24 to 5V step down converter to power the arduino itself. I had issues with my laptop and RPi not providing enough current to keep a stable voltage to the arduino itself.

I have a rather UGLY prototype built on perfboard now, but a finished board shouldn’t be too terribly expensive. If it is something you guys would like to pursue just let me know and I will share my progress.

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Share progress please! :grinning: :+1:

I’d be interested in this if it develops to something fairly inexpensive and easy to install. Definitely share your progress, please. :smile: