Adding a Touch Plate and Modifying the Tailstock Mount for the Rotary Axis on My Gatton CNC

TEF and Headstock

With the rotary axis now fully operational, it’s time to add touch plate functionality and modify the tailstock mount on my Gatton CNC’s rotary axis. Read More

Modifying the tailstock mount

The tailstock mount is 2 long pieces of t-track with an MDF spacer separating them. It mounts the tailstock just fine, but getting the tailstock lined up with the center of the chuck ended up being a giant pain. I needed to come up with a solution, and luckily the manufacturer of the tailstock gave it to me.

Recess in the Tailstock Housing
The recess in the bottom of the Tailstock Housing

The tailstock housing has a slight recess cast into the bottom of it. This recess is about 3/32” deep, and just over 1 1/2” wide. I found that a piece of 1/16” thick flat aluminum bar stock would fit in that recess perfectly, and give enough clearance to allow the tailstock to slide back and forth when I had the mounting bolts loosened. I had a piece of 1 1/4” wide, 1/16” thick flat stock, so I cut a piece to length and mounted it on the MDF section of the tailstock mount, making sure that once mounted, the tailstock would line up with the center of the chuck for the full length of the tailstock’s travel. With that lined up, I mounted it to the MDF with 1 1/4” long wood screws.

The mounted tailstock
The mounted tailstock – much easier to properly align with the chuck.

I should mention here that I probably should have gone with a piece of 1 1/2” wide flat stock, but I didn’t have any on hand. The 1 1/4” wide stock works just fine – I just need to make sure that I hold the tailstock firmly in place while I’m tightening the mounting nuts. With that sorted, I moved on to the next modification.

The touch plate

Ever since getting the rotary axis kit, I’ve wanted to add touch plate functionality to it. Guessing on where the tip of the bit was in relation to the center of the stock was marginal at best, and completely off at worst. This is especially true if I needed to do a bit change.

Touch plate for Rotary Axis
My idea for a rotary axis touch plate

I got into SketchUp and drew out a couple of ideas for touch plates that could be put into the chuck, leveled, then used like any other touch plate could be. I even showed screen captures to a couple of friends, and they thought it was a good idea. Then one day, while out in the shed, I spotted my Triple Edge Finder from The Maker’s Guide. Something clicked in my brain, and I realized that I didn’t have to make anything, as I already had everything I needed.

In the video, I show you the process I used to set up the Triple Edge Finder for use with my rotary axis. I go into detail about how I figured out which touch plate thickness to use, how I modified the touch plate script, then how I edited the script in Mach3 to program the Auto Tool Zero button in the Program Run screen. I also give you a link to the source of that script.

Zeroing Z with the TEF
Using the Triple Edge Finder on the headstock housing to set Z zero

The main thing to remember when modifying the script is to ensure the retract height in the script is set higher than the thickness of the touch plate in order to prevent damage to the CNC.

Check out the video

summing up

In a nutshell, that’s about it. I’ll not go further into it here. It’s better to watch it in the video than to try to type it out here. Suffice to say, I’m very happy with the result. Between the modified mount and the touch plate, I no longer have to use my machinist’s scale to mount a piece of material into the chuck of the rotary axis. I can now just find the center of the material with my center finder (link below,) put the material in the jaws of the chuck, line up the tailstock with the center of the crosshairs, and tighten everything down.

Here’s a link to The Maker’s Guide, where you can check out the Triple Edge Finder for yourself. I really love this tool!

http://www.themakersguide.com/home/products/triple-edge-finder-2

Here’s a link to Dave Gatton’s website, where you can get info on a Gatton CNC kit of your own.

http://www.davegatton.com/

So that’s it! Thank you very much for stopping by! As usual, if you have a question or comment, leave it in the comments section below. Or, if you’d prefer, go over to the Contact Us page and submit it to me there. Remember to click that link up at the top of the page to check out my T-Shirt shop!

Until next time, take care and have fun!

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The Mount and First Run of the Rotary Axis on My Gatton CNC

Mounted Rotary Axis
The Mount Base

With the rotary axis set up and tested, it’s time to mount it on my Gatton CNC. When I built the table for my CNC, I included a cutout up front specifically for this project. If I made one mistake, it was in not making the cutout wider. I do regret that now. But, it’s okay – I’ll work with what I got. Read More

In the video below, I describe how I screwed a 48” long piece of kiln dried 2×6 to the bottom of my table frame. I then cut 2 pieces of MDF to sit on top of that 2×6. I sealed the bottom and all 4 edges of both pieces of MDF with 3 coats of shellac based sanding sealer.

I then positioned the first layer of MDF, drilled the pilot holes, then screwed it down to the 2×6 with 1 1/4” long exterior grade wood screws. I then sealed the top surface of that piece of MDF with 3 coats of sanding sealer.

When the 3rd coat of sealer was dry, I positioned the second layer of MDF, drilled pilot holes, then mounted it with 2 1/2” long exterior grade woodscrews, driving them through both layers of MDF and into the 2×6. I drove them into the top layer of MDF fairly deeply in preparation fro the next step – surfacing the whole thing with the CNC. After surfacing it to make sure the top surface was parallel with the X axis travel of my CNC, I then sealed it with 3 coats of sanding sealer. I then let everything cure for 24 hours before moving on.

The Headstock Mount

The headstock mount itself is simply 2 pieces of t-track I had leftover after cutting my spoilboard t-track to length. I spaced them with 3 pieces of MDF, cut from the same piece that the tailstock mount was cut from.

Mount for the Headstock
The completed, sealed headstock mount
The Tailstock mount

The tailstock mount is 2 long pieces of t-track with an MDF spacer separating them. All of the MDF pieces were given 3 coats of shellac-based sanding sealer, and fastened with 2 1/2” exterior grade woodscrews.

Mounted Rotary Axis
The headstock and tailstock mounted and ready to use
check out the video

In the video, I show you the process I went through to set the CNC up for rotary axis use, then show how I mounted a piece of cedar in the chuck. I’m still learning this rotary axis, so if you have any tips or tricks to share with me, I’d really appreciate them.

In a nutshell, that’s about it – with the exception of actually running the g-code. I’ll not go into that here. It’s better to watch it in the video than to read my dismal description of what happened. Suffice to say, I’m very, very happy with the result.

First Project Finished
The finished first project

Something I did NOT go into in the video was modeling the part I cut. It was way, way out of the scope of the video. I will be uploading videos that cover that topic later on – count on it.

So that’s it! Thank you very much for stopping by! As usual, if you have a question or comment, leave it in the comments section below. Or, if you’d prefer, go over to the Contact Us page and submit it to me there. Remember to click that link up at the top of the page to check out my T-Shirt shop!

Until next time, take care and have fun!

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Mach3 Settings for the Rotary Axis

Almost ready!

With the rotary axis assembled and ready to go, it’s time to set up Mach3 to work with it. Rather than go through the entire process here, I’ll give you some of the highlights and refer you to the video on my YouTube channel, linked below. Read More

I will, however, include screen shots of all of the relevant Mach3 windows that I went through in the video. If you right-click the pictures, then select “Open in New Tab, a full-sized picture will open in a new tab on your browser. Feel free to download and save these pictures for future reference, but please don’t post them online without talking to me BEFORE you do it. I would appreciate it.

Initial Steps

The first step is to create a separate Mach3 profile for it. We can clone the profile we use now and modify that clone, or we can clone one of the factory profiles and modify that clone. No matter which way we go, we’re going to have to enter and change a bunch of settings, so I chose to clone the factory Mach3 Mill profile. You don’t want to use Mach3 Turn, because that’s designed for a CNC lathe. A rotary axis is not a CNC lathe – there are some major differences. The rotary axis is just an accessory to the CNC router, so I cloned the Mach3 Mill profile.

The Settings

The second step is to Select Native Units.

Right click, and select "Open in New Tab."
Select Native Units

Third is to activate the Motor Outputs one by one.

Motor Outputs
The Motor Output settings

Next is to make sure the A, B, and C axes are configured as ANGULAR axes, and there is no checkmark next to Home Slave with Master Axis box in the General Configuration window.

Right-Click and select "Open In New Tab"
General Configuration Settings

The Really Important Bits

Fifth is the motor setup, which we’ll do by going to the CONFIG menu and selecting Motor Tuning. The A axis is the axis that may cause the most confusion. The thing to remember is that the other axes are LINEAR, and they’re based on Steps Per Inch. The A axis is ANGULAR, and it’s based on Steps Per Degree. So we’ll need to get some info and do a little bit of math before we can enter the Steps Per for this axis.

Motor Tuning X Axis
Motor Tuning Settings for X axis
Motor Tuning Z Axis
Motor Tuning Settings for the Z axis

First, we’ll need to find out how many steps our motor takes to turn one complete revolution. In the case of the Xylotex motor, that number is 3200 steps. So we have our 3200 steps to turn the stepper motor 1 complete revolution. Now we need to know the drive ratio of the rotary axis. In the case of my Sunwin unit, that ratio is 6:1 – meaning it takes 6 revolutions of the stepper motor to turn the chuck 1 complete revolution. So to find out how many steps per degree to enter in the Steps Per box in the Motor Tuning window, the math looks like this:

3200 steps X 6:1 drive ratio = 19,200 steps to turn the chuck 360 degrees, or 1 complete revolution.

(3200 X 6 = 19,200)

19,200 steps divided by 360 degrees in a circle = 53.33333 recurring.

(19,200/360 = 53.33333 recurring.)

A Axis
Motor Tuning settings for A axis

So, I now know that the Steps Per for the A axis is 53.33333. I entered 5 places to the right of the decimal only because I don’t know how many Mach3 will let me enter, and I really don’t know if going any further than 5 places to the right of the decimal will matter. If it turns out that it does matter, I can come back and add more.

For the velocity, I entered 2500. Remember that we’re not working in inches per minute in this case – we’re working in DEGREES per minute. For instance, if I set the velocity at 360, that means it will take 1 minute for the axis to make one complete 360 degree revolution. That’s way too slow. At 2500, it should take less than 10 seconds to make 1 complete revolution, which is not very fast at all. Next I’ll set the acceleration to 485 degrees per second. That’s not how fast the axis will turn – that’s how fast it will accelerate to the speed of 2500 degrees per second. Also remember that the speeds we’re setting in this window are the rapid movement rates – NOT the normal feed rates.

Just a Few More To Go

The next step is to make sure there are no axes slaved together. Whether you make any changes in the Slave Axis window or not, it’s time to restart Mach3. Before you do, however, go back to the CONFIG menu, and click Save Settings so that all of these changes will be written to the hard drive and saved.

Right-Click and select "Open in New Tab"
Slave Axis settings

With the profile made and the settings entered, we’re ready to test the rotary axis. Pay attention to the direction of the chuck’s rotation. Positive Rotation should be counter-clockwise. So if I stand in front of the machine, the top of the chuck should appear to be turning toward me. If it’s not, I’ll have to reverse the direction of that stepper motor by going up to the CONFIG menu, selecting Homing/Limits, and putting a checkmark in the Reversed column, next to A Axis.

Next comes programming some hot keys for the rotary axis. If you use a pendant or video game controller, now is the time to program that as well.

Right-Click and select "Open in New Tab"
Mach3 System Hotkeys screen

The next 2 settings are used to make sure the toolpath display in Mach3 will display correctly, and the feedrate will be calculated correctly.

First we’ll enter the correct settings in the Toolpath window. Don’t forget to go to CONFIG, and click Save Settings again.

Right-Click and select "Open in New Tab"
Toolpath Configuration settings

Next click the Settings tab at the top of the screen, and look at the top, right corner for Rotation Radius. Each time I chuck something into the A axis, I’ll want to enter the RADIUS of the piece of material in that DRO in the A Axis row. So if I have a piece that’s 1.5” square, the rotation radius will be .75. So I’ll click the DRO next to A, type in .75, then hit the ENTER key. Now when I go back to the Program Run tab, to the right of the 4 DRO, I can see that the Radius Correct LED is lit up. That lets me know that I remembered to enter the rotation radius into the Settings screen, so my toolpath display should actually display the toolpath correctly. It also means that Mach3 will now calculate the feedrate called for in the g-code correctly. Again, this will have to be done each time we put a piece of material into the chuck of the rotary axis.

Right-Click and select "Open in New Tab"
Settings Tab

Made it!

That’s a lot of information, I know. It made for a very long video, I know. There’s nothing inherently difficult in setting it up – there are just a lot of things to remember to do. The single hardest part for me was in remembering to think in terms of degrees, rather than inches. I’m working on that, and it is getting easier.

Summing Up

If you’ve stuck with me this far, I’d like to say thank you very much. I know that videos and articles like this are as boring as watching paint dry, but it’s impossible to put this much info into a short presentation.

In my next article, I’ll talk about how I mounted the axis on my Gatton CNC, future mounting plans, and hopefully I’ll get to do some cutting on it! Thanks for stopping by!

Here’s a list of all of the parts I bought to get a rotary axis for my Gatton CNC, with links so you can check them out.

Xylotex Stepper Motor

Sunwin Hollow Shaft Rotary Axis

POWGE 10 Teeth HTD 5M Synchronous Pulley

(Make sure to select 6.35mm bore diameter, for 15mm wide pulley, and choose the number of pieces you want.)

LUPULLEY HTD 5M Timing Belt

(Be sure to select 15mm belt width and 355mm belt length.)

As usual, if you have a question or comment, leave it in the comments section below. Or, if you’d prefer, go over to the Contact Us page and submit it to me there.

If you’d like more info on a Gatton CNC kit of your own, check out Dave Gatton’s home page here.

Until next time, take care and have fun! 

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Introducing the Rotary Axis for my Gatton CNC

I’ve wanted to add a rotary axis to my CNC since I built my first Shoestring Budget CNC back in 2015, but they were just too pricey. I looked into a couple of options for a home-built unit, but never found one that I really liked. I downloaded a few sets of free plans, and eventually bought the plans being offered by Dave Gatton, here on his website.   Read More

I got Dave’s plans and started looking into them, getting more and more excited as I did so. I even went ahead and bought a Xylotex stepper motor to use in the build. Then I immediately got slammed with work, and it had to go on the back burner. When I started my Gatton CNC build back in June of 2017, the rotary axis project got pushed even further back. Finally, in December of 2017, with my Gatton CNC build finished, I decided that I had waited long enough, and that I was going to have a rotary axis for my CNC by the end of 2018.

The Search

The problem was that by the time I got back into the plans to build the Gatton Rotary Axis, prices had gone up quite a bit. As I started adding up the cost of all the parts, I wondered if I had waited too long to get going on it. I then decided to price a few rotary axis kits being offered online and do some comparison shopping. I was surprised by what I found.

I found complete kits ranging from $150 to $375. Some of those kits came with a tailstock, and others did not. I did a little bit of looking around, comparing the pros and cons of each kit I was looking at, and decided that I would purchase a rotary axis kit, rather than build one. My thinking was that the major part of the building was done for me, for the same amount of money (or less in some cases,) as a pre-assembled kit. Also, by this time, I was getting a little tired of building CNCs, and wanted to focus on actually USING the CNC I had worked so hard to build.

With that decision made, I then set out to choose a rotary axis that would work with my Xylotex drive box. That proved to be harder than I thought it would be. You see, the Xylotex drive box I have is a 4.0 amp system. The only rotary axis kits I could find were 3.0 or 3.5 amp kits. Now I’m not an electronics guy. My electronic knowledge is rudimentary at best – downright barbaric at worst. I do know enough to try to match a motor’s voltage and amperage to that of the power supply, however. I just wondered if one of the 3.5 amp motors could be used with the 4.0 amp Xylotex drive box.

I emailed Jeff at Xylotex, and asked him if one of these motors would work with the drive box (I sent him the spec sheet on the motor in that email.) He warned me that while the motor would physically turn, it would tend to shudder, stutter, and jump as it did. It would also tend to overheat in a short amount of time. He recommended that I didn’t use it, but rather to swap it out for one of the Xylotex motors. (I had reminded him in my initial email that I already had a spare Xylotex motor, which I had purchased to build a rotary axis with, so there was no opportunity for another sale here – he knew I had the spare motor on hand. I have dealt with Jeff many times in the past, and I just don’t think he’s the type to tell someone a flat-out lie for a $40 sale.)

So, I finally decided on which rotary axis I wanted, then ordered it. I chose this Sunwin CNC hollow shaft rotary axis with100mm 4-jaw Chuck and 65mm tailstock through Amazon.com. 

The Sunwin Hollow Shaft Rotary Axis Kit as purchased.

I chose this kit for two major reasons. First, when I ordered this kit, they were offering free shipping. Second was Amazon’s return policy. I knew that if I received a defective unit, I’d have an easier time returning or exchanging it through Amazon than I would through someone on eBay or Ali-Express. I did find several other rotary axis kits that were less expensive, but those two factors were what decided it for me. For example, I found a solid shaft rotary axis kit, without the tail stock, that was $150. However, reading the fine print, the shipping from China to the US was $195! More than the cost of the unit! And I’d still need to buy a tailstock! The Sunwin kit was only $24 more, and had the tailstock, plus the hollow shaft. I decided to go with that unit.

Sunwin hollow shaft headstock

I received the kit about 10 days after ordering it, and was chuffed to bits when I got the boxes open. I got the Sunwin motor off with no problem. I got the Xylotex motor mounted with no problem. I took the timing belt pulley off the Sunwin motor with no problem. I went to put it on the Xylotex motor, and had a problem.

The Parts Chase

The motor shaft on the Xylotex motor is 1/4” diameter. The motor shaft, and therefore the bore on the pulley, is 8mm. Yup – that’s too big. If I were a machinist with a metal lathe, I could have made a sleeve to adapt the Sunwin pulley to the Xylotex motor. Well, I’m not a machinist, and I don’t have a metal lathe. So, I went online and searched for the proper pulley to fit the belt and my stepper motor.

It was harder to find than I thought it would be. I checked all of the usual websites (McMaster-Carr, etc…,) but came up empty. I finally found it on Ali-Express, here.

A word of warning here. If you ever need to order something from China, make certain it can be shipped before February 1st. Most of the manufacturing in China closes down for 2-3 weeks for the Chinese New Year celebration. I didn’t know that, and ordered my pulley on February 7th. It shipped Feb 28th, and I received it March 9th.

With the timing pulley finally in hand, I was excited again. It fit the Xylotex motor perfectly, and tightened securely. Then I ran into a second problem. See, the Xylotex motor is not only higher amperage, it’s also physically longer than the Sunwin motor – by about 1/2”. That put the end of the motor right in line to interfere with the bolts that mount to eh chuck to the faceplate. Awwwww, crumb… I needed a longer timing belt.

Thankfully, I didn’t need a much longer belt. I got online (again) looked for 15mm wide high torque timing belts with a 5mm pitch, and found them in short order. I decided to order 2 different sizes. I ordered one that was 5mm bigger, and one 10mm bigger. I know my luck – if I had ordered the 5mm longer belt, it would have been too short. If I had ordered the 10mm longer belt, it would have been too big. I ordered both, and that basically confounded the CNC gods enough that the 5mm longer belt fit perfectly. With all of the parts finally in one place, I assembled everything perfectly, and got it ready to take outside to test it.

The completely assembled headstock, after modifications

Well, actually, I did have to do one last thing to the headstock, but… well… This article is getting pretty long. Check out the YouTube video I posted below, and you’ll get all of the details.

The Bottom Line

So, in summing up, yes I now have a rotary axis for my Gatton CNC. So far, yes, I do like it. Would I do it again? Well, knowing now what I didn’t know then, yes I would. I would time things a little differently, but yes I would.

Here’s a list of all of the parts I bought to get a rotary axis for my Gatton CNC, with links so you can check them out.

Xylotex Stepper Motor

Sunwin Hollow Shaft Rotary Axis

POWGE 10 Teeth HTD 5M Synchronous Pulley

(Make sure to select 6.35mm bore diameter, for 15mm wide pulley, and choose the number of pieces you want.)

LUPULLEY HTD 5M Timing Belt

(Be sure to select 15mm belt width and 355mm belt length.)

In my next article and video, I’ll get into Mach3, and show you how I created a new rotary axis profile, and what settings I used to get my rotary axis working with my Xylotex drive box.

As usual, if you have a question or comment, leave it in the comments section below. Or, if you’d prefer, go over to the Contact Us page and submit it to me there.

If you’d like more info on a Gatton CNC kit of your own, check out Dave Gatton’s home page here.

Until next time, take care and have fun! 

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