Adding a 4th axis to micromill

[MadeForThat]

I have already initiated this project, but figured I would document what I have done thus far with some pics. I was able to snag a sherline rotary table off of ebay for a pretty good deal. It had a stepper and an encoder on it, but i opted not to keep the encoder, as it has its own set of difficulties. I replaced it with a thumb wheel that I turned and knurled at work. The next problem was mounting the table on to my mill's bed. I made up some T nuts at work, (just buy T nuts lol) and drilled in some new mounting holes. After shortening some 10/32 bolts, the table mounted firmly on to the bed As for controlling the stepper, I had picked up some random electronics from a gentleman at a garage sale. Among this "junk" was a stepper driver that coincidentally uses the same L2**** chip that the control board uses. I mounted that under the spindle controller. I have not tested the two together, but that is coming soon In order to control the stepper driver, I will be swapping in a nextstep card for my micromill's Denstep. The reason for this: the nextstep card has 4 step/dir outputs where the denstep only has 3. The Nextstep card is from my lathe anyways, so I'm not loosing any function by downgrading it to a denstep card. (I think/hope) On the Nextep card, there is a header with access to all step /direction output. See: viewtopic.php?f=54&t=3576 This will be easy to make a suitable connector, and I can run that directly to my step driver.

[MadeForThat]

So if you were thinking that this seems to easy--> you were right... I was able to get the mill jogging with the nextstep card, and i was getting pretty excited that it was going to be easier than I thought. When I went to enable the 4th axis, I was unsurprisingly hit with the error pictured below. It does not seem that any of the micromill profiles have the 4th axis as an option. (I am assuming the "micromill" is the successor/NS to the micromill2000) I think this means I will need to modify one of the profiles that does, and change the machine parameters to match my hardware. Not super excited to learn about mint, but I'll take any opportunity to learn a new skill. I have not started reading up on this, so if any cnc guru's have recommendations for reading, I would be very appreciative.

[TDIPower]

The guys at denford will know best BUT I wonder if you could use a Novamill or microrouter with 4th axis and just rejig the settings within those files to those of the micromill eg speeds and sizes.

Pete

[MadeForThat]

Yeah, i was actually wondering if there were more settings than what are accessible to change under machine parameters? If not I think i can just take some pictures of the micromill parameter pages, edit the novamill to match, and then select novamill as the device. No need to even open a .mex. That would be pretty slick

[TDIPower]

when I was testing the NS board I have to upgrade my Lathe, I just dropped it straight into my Mircorouter, VR did it's erasing flash thing on connection at it worked straight off for the microrouter. so the board just works on what it's told to do, obviously I didn't try rewriting anything for this it was just to check functionality.

I very much doubt you will hurt anything just swapping the settings and giving it ago, Just looked on VR the IV axis has a few options A,B,C (1,2 or 3). Not sure what that would be for though or where a home switch if fitted could be wired to.

[MadeForThat]

Everything seems to work great! I will be wiring in everything this week, and i will be able to do some testing next weekend!

[TDIPower]

great stuff!!!

[MadeForThat]

Well I always seem to think things will just fall into place. Here is another minor detail I need to sort. my stepper driver is for a 4 wire bipolar motor. I have an 8 wire stepper, wired into 5 wires with a ground for a total of 6 wires in the cable. This is a cool opportunity to learn about bipolar series and bipolar parallel, and I have yet to decide on which I plan to rewire the stepper to match. NOTE: this is not a denford sourced motor, and is likely from a Taig or MAXNC mill, based on the table mount holes that were on it. (These 2 companies used sherline rotary tables, but would retrofit their own controls, hence the odd stepper config.) This section of this post is probably not applicable to most. below are some pics that I am using to map my wires haha

[TDIPower]

really loving this work. I've never used 4th axis and can't wait to see this in action, I will be bouncing you the questions if i decide to do something like this in the future!

Pete

[MadeForThat]

We have motion!! Tonight I got it all wired up and turning! It seems to struggle with torque, so I am starting to regret wiring my stepper in bipolar series (lower power consumption and torque) I plan to try hooking in a new power supply for that drive, as I would like to make sure it is maxed out on available power before I go back and redo my connections. Not sure if the vid will post below, hopefully

[MadeForThat]

More power did the trick! I used a laptop power supply, giving 19.5v at 4 amp. Much more than required, but within the range that both the motor and the controller could function. Wiring in the new supply was easy, I ended up just running it in parallel with the ac transformer, as this is controlled by the main power relay and has a fuse. (hopefully I don't blow fuses under load, but I wont know until I do) There is a part of me who is disappointed that I did not run a new fuse and linked it in a uniform way, but unfortunately that part was outweighed by the rest of me who wanted to get it all running. Amazon has a lot of "DIN fuse holders" so if I do blow a fuse, I will be taking the time to run a separated line. I will start programming a little something this week, and will try to get a video uploaded.

[MadeForThat]

I STILL HAVEN'T DONE MUCH MORE THAN A FEW SMALL CUTS!!! I have been in the process of moving all my projects to my shop, and have not had much time to program some fun stuff yet. I have had a little time here and there to finish mounting my mist cooling, dial in the steps per degree of the rotary table, fit a sherline spindle handwheel for turning the er16 collet nuts, mounted a taig 3 jaw chuck from eBay, mounted Y axis bellows, and I think that's pretty much it for the winter.... Looks great but I haven't even really had any fun cutting with it yet! I guess collecting accessories is a sherline problem.

IMG_20200402_194105.jpg (127.97 KiB) Viewed 24325 times

[TDIPower]

Thats looking really good well done! Post up when you have more to show!

Pete

[pokerdetroit]

Nice work! I have tried to get my 4th axis going but the mint files have scorched my brain. I got it to turn 1 and then I overwrote the working file. Any chance you could share you setting and mint file . And pics of connection to Nextstep for estop to 4 axis card. Thank you Steve

[MadeForThat]

Hi Steve, So I actually didnt modify the mint file, that was absolutely going to take more effort than what I ended up doing. So as TDIpower mentioned above, you can change the profile for your machine to another denford machine that had a 4th axis as an option. You will need to reenter all the settings for your actually machine, and over write what is in the microrouter settings, once this is done, you can connect and the NS will reflash and you should then see the A Axis show up for jogging. I have yet to program with it, but as long as you set your steps per rotation value in machine settings, it will turn the right amount. I just took a pic of each window in my micromill 2000 machine settings, and then selected the microrouter and set it as current machine, changed the values that were different, enabled the 4th axis, and it was functional From my messing around, the ABC/123 for enabling the rotary, is to select which axis you rotate around. a/1 corresponds to if the table is facing left or right as you look at it from the front, 2 corresponds to if the table were facing forward or away, and 3 for up and down. I don't know that it will mater if you are hand programming/indexing, but probably does if you are generating your program automatically. I don't know to be honest, but I use 1, and have my rotary mounted on the left hand side of the table. If any denford pros can confirm or reject my guess about the mystery abc/123 rotary setting, that would be cool. Only downside to adding the rotary this way, is you loose the vr model of the micromill, because now you have a microrouter.... not that big of a deal, it just takes a little bit more care and attention to make sure the gcode wont crash. As for the E-stop wiring, you may want to confirm this, but I think the 110v transformer is cut with the estop, so if you wire in the way I did, then it should cut power when pressed. It might take a fraction of a second just to burn the power in the laptop PSU. Either way, the NS control board is definitely stopped with the estop, so the motor controller will stop receiving pulses, and therefore the motor will stop regardless.