Excitech CNC Modifications Thread...

[Eclipze]

Originally Posted by mecanicu if you ar thinking on selling the board or the schematic's i'm interested...

I would have offered, but I can't provide this anywhere near as cheap as what you can get commercial units. CNC electronics is a "very" competitive market with a lot of gear available on the market and "a lot" of cheap rubbish.

If I was making 500+ of them, then I could buy parts in bulk and do a production run with good pricing. However including the VFD speed controller, there is just over 200 parts to solder and about 3 hours labour to build and test just one set.

Just to give some ballpark figures... doing a quick calcuation there is around AU$100 worth of parts (not including postage and only approximate). If there were 3 people paying $250 + postage, then I'd consider making them and check the cost details (this isn't what I started this thread about for!). But keep in mind you could probably hunt around for something worth trying and rig it up for half the price. But you would really have to compare apples with apples when it comes to what the boards do. Some will need an additional 5V power supply, others will require extra resistors to cope with the 24V signals. Most won't have a digital watchdog circuit and VFD speed controller. A lot don't even have opto-isolators, and some of those that do don't even have the ground isolated anyway (bad design).

[Eclipze]

SHM0609
Mach3 with ShuttlePro2 used as Control Pendant

The fine people that support Mach3 have written a plugin to use a ShuttlePro2 Pendant for controlling the CNC. The ShuttlePro2 is like a joystick, whereby it's a USB device that provides configurable buttons and a jog wheel. They are used by PC users for things like audio/video engineering/mixing etc...

I have mine configured so I can jog an axis using the wheel (several speeds as you turn the ring) and the centre wheel gives fine precision steps. I pick which axis to jog using a button. Also have the start/pause/stop/rewind buttons setup, as well as for setting DRO zeros and inc/dec feedrate. I want to have inc/dec for spindle RPM too, but I'II have to look into doing this via macros as they aren't in the drop down lists to configure.

Very easy to setup.

1. Download the plugin and setup document from Artsoft.
http://www.machsupport.com/plugins.php
2. Run the ShuttlePro.m3p file, which copies a DLL to a Mach3 directory.
3. Run Mach3 and then go through the Config Plugins menu option.
4. Configure what you want the buttons to do. I have attached a screen shot of my settings for reference.

I have a button for "Cont/Inc Center Mode" so I can set the centre wheel to step mode. Wish I could set it as a default. I have to hit the button once on startup, after which each click of the centre wheel inc/dec the selected axis by the value I set in Mach3 for incremental steps. I have it at a nice fine resolution, so I can accurate pin point tool bit.

The tool zero modification I done earlier is a little trickier to assign to a button, but still very easy. Greolt (person responsible for the zero tool function) provided the following info to set this up...
"- Copy your zero script to a notebook file and save it as M650.m1s
- Place this file in Mach3 / macros / Mach3mill folder (or the folder with the name of the profile you use)
- Then in the Shuttle plugin assign a button to "Custom macro #1" and put 650 in the Macro number 1 box
- That should do it. Just remember if you ever alter your zero macro, to do it in both places. Button Script and Macro folder."
So Operator-->Edit Button Script, click the Zero Tool button and you'll see the script. Copy that to a file and follow as above.


The youtube video below shows Greolt using his ShuttlePro2, demonstrating the zero tool mod, then the X/Y laser position mod he has also done.

YouTube- Laser Zero finder

YouTube- Laser Zero finder

There is also a forum thread at Artsoft (providers of Mach3), which you can find here...
http://www.machsupport.com/forum/index.php?topic=1220.0

I bought my ShuttlePro2 on ebay, from ebay sellar "e.baybuy" US$85 + postage. Very quick with posting and was quick with a response when I asked a question.

This is going to be a very handy mod!!

[Eclipze]

SHM0609
Leveling the machine.

There was slop in the Z-Axis, the spindle wasn't vertical (both X and Y directions) and the table was far from level. Apart from introducing wear on the bearings and undesirable tool tip cutting/wear/finish... cutting a straight edge square shape would be impossible. Paul3112 and Nigel gave me a big hand to squaring up the machine - actually, they did a lot of the work

We first had to get the Y-Axis rails level with each other. Using a precision spirit level, the feet were shimmed until both rails were level. The gantry provided a small amount of deflection when resting in the middle of the travel (<0.1 degree), so it was moved to the ends as necessary. It was quite important to keep the spirit level orientation the same when measuring both sides of the machine, and the bubble referenced from the same line. The rails were now level front to back, but not yet side to side.

A very flat slab of marble was put on the table and the feet shimmed until it was level side to side. This provided a perfect reference for the rest of the alignment. Fortunately the X-Axis rails were good, so the Y-Axis rails didn't need any shims to adjust the gantry height.

The Z-axis was pretty bad. It had noticeable slop, which you could notice when someone was applying pressure to the spindle in various directions. It was slop in the bearings too, not deflection of the gantry - although we did notice a small amount in the gantry plate. The slop was so bad that the ball screw thread had uneven pressure on it and caused cavitating as it turned. We measured an oscillating error with the dial gauge as it moved up and down the rails. Having removed the covers, the linear bearing adjustment screws were tightened as necessary - both for the Y-Axis and Z-Axis carriage. Made a very noticeable/measureable difference :-)

Using a dial gauge mounted in the spindle collect, such that it spun around in an arc measuring the hieght of the marble plate, the Z-Axis plate was rotated in place and shimmed with foil to get the elevation corrected. Resulting in very straight up/down travel. After these final adjustments, the dial gauge could be rotated in an arc from the spindle with a radius ~100mm with <0.02mm variance in measured height. Simply outstanding.

I've got some adjustable height feet for the base today. I wish I had these yesterday, but I didn't understand just how much difference a shim the thickness of a piece of paper made to getting the rails level. So a more permanent adjusting footing is yet to be put in place. Next will be machining the bed nice and level. It's appalling at the moment with the black rubber strips glued on the deck... over 1mm height variations across the table at the moment. Getting there!

Hope the info is useful.

[Eclipze]

SHM0609
Lubrication

I've spoken with a few people and done some reading on this topic. I also had a friend that is a seasoned fitter and turner come out and have a look at the machine. You can lubricate these with either oil or grease, although which you chose will depend on your application.

For machines that get worked a lot and frequently, you are better using an oil. Oil is good, because it helps to flush out the bearings of any contaminants. It's also lighter and more appropriate for higher speed traversing. But you need to have an oil feed, as it drains off. Which means a reserviour and piping lines to the points where lubrication is needed. It can be messy too, as they used oil has to go somewhere.

Grease lasts a lot longer, as it sticks around. The HWIN data on the linear slide bearings advise the grease need to be changed every 100km of travel. Grease is sticky, so it will collect any material floating around. So there is more chance of something working it's way into the bearings.

I won't have a high use for my machine... might sit there for 2 weeks untouched, then get 4 hours of use. I'II probably re-grease the bearings every 3 or 6 months, depending on how much use it gets etc... It's also a perfect chance to conveniently inspect the bearings and check for binding on the rails at the same time. If I used oil, I probably wouldn't go that far and leave a maintenance check for a rainy day. Grease suits me more than dealing with oil, and I can use one grease for all lubrication requirements. I'm using Thomson LinearLube, which is a grease lubricant with P.T.F.E. I've put this in a typical hand operated grease gun for dispensing.


Each axis has a ballscrew nut, which is held in by 6 bolts. You will need to take the dust covers off the X and Z axis, and a side panel on the machine to get underneath to the Y axis ballscrew. I'd recommend to take these off before you start greasing. This gives you the freedom to easily push around the gantry for lubrication, as well as to check everything moves smoothly, no binding. Also handy as once you start greasing, you won’t want to grab your tools hahaa…

The Y-Axis, the one that moves the gantry, sits on 4 linear carriages (2 each side). These carriages are fitted with M4 oil nipples (M4 = 4mm thread). I couldn't push grease through these... I tried. I looked for M4 grease nipples to replace the oil nipples, however I had a lot of trouble finding them. Everyone has M6, but no-one had M4. Even if I found them, I suspected there wouldn't be enough clearance to get the grease gun clipped on. So instead, I drilled a 1.5mm shaft down a M4 bolt. Then used some tubing to join it to an M6 grease nipple thread. Worked a charm, and the grease easily squirted through. Only saw a slight film of oil come out the carriages... was probably dry in them already. Given the ballscrew is unbolted (and spun up one end out of the way), you can grease/moved the gantry to get the grease to move through the balls. I also smeared some grease on these rails. Most of it gets wiped off with a pass, but a thin film is left on the rail.

The X and Z rails are rod bearings. Smear the grease on and push side to side to run it through. Those bearings don’t have a greasing point.

The ballscrews have an M6 thread to fit a grease nipple. However Excitech don’t leave room to fit a grease nipple to the X and Z ballscrews… you have to remove the ballscrew to get access to it! Once you screw in an M6 grease nipple, you can squirt through the grease and flush out the old stuff. I also smeared some grease on the leadscrews. I didn’t see any old grease expell from the Z or Y axis ballscrews. Only the X-Axis. Little concerning to not see.

It was good to know after all the levelling work done that all the axis moved smoothly and without binding.

[Khalid]

Really Like the modifications.. Thanks for posting and contribution...

[Eclipze]

SHM0609
Adjustable Feet

I didn't realise just how important it was to have the CNC level until I could see how far out long rail were to start with (see previous post). If the Y-Axis rails are not running level with respect to each other, the spindle will have variable height across the table. It effects everything, even when it comes to plunging or drilling perfectly vertical. As a reminder, just one additional sheet of paper under one of the feet had an effect that could be measured on the table.

The floor certainly isn't level and I doubt the CNC is completely level either. The amount of different between shimming the four feet is up to 8.5mm on my machine.

I decided to get some adjustable feet for a more permanent solution. I eventually found these monsters, 90mm in diameter with M12 bolts. They also have a rubber layer on the bottom, perfect for a good grip and uniform loading. Very easy fit and the CNC isn't moving.

So easy to adjust the height of each corner now. I wish I did this first.

[Eclipze]

SHM0609
Leveling the Bed

The top surface is covered by some sort of dense foam material, glued on top of the T-slot. It's 9mm think and soft. Not very good for clamping, as you can literally tighten one side of a part first and dig into the foam. Leaving the job level. You also loose usable Z-Axis travel having it. The most annoying thing is the top level of the material is not level. I've measure just over 1mm height variation. So I machined half of it off, so now it's nice and flat A lot less absorbing too.

I used a tool bit that gave a nice 100mm diameter cut, so I could level one whole strip at a time. Slow 300mm/min feedrate, to give a neat finish. I was amazed at just how much mess that stuff made.

[BEERMAN]

Eclipze
I have an excitech SHG1224 model and i have recently been having troubles with a tool problem when using area clearance. The tool enters outside the line then corrects itself and completes the cut leaving a gouge at the start. No good.
Have been trying to fix this problem for a month now and have been looking mainly at DSP and programing. But have had no success.
Yesterday, i ran a program at very very slow feed rate and the gouge was significantly reduced. Running the program at 2000mm/min resulted in the gouge re appearing at approx 2mm outside the line. I think now it must be in the gantry or axis that when the tool starts its cut it is moving/flexing!!!!
This lead me to do this search and find your thread. I actually use to have the shg0609, similar to yours.
My new machine has the same Italian spindle as yours.
When i remove all covers etc.
I can if i grab it and force it i can get some movement in the spindle. Looking at it, it seems to be more where the machine attaches to the x axis with the bearings....I honestly wouldn't think this movement would be enough to cause me problems, but maybe it is...how much is too much movement.. ideally none would be great but these are not top end machines so i realize that is probably not realistic. The machine is only 18 months old.
Any clues or hints here would be grateful..
Everything seems to be very tight nothing has come loose and i haven't always had this problem. Do you think a bearing needs adjustment, and how can you tell what is correct etc..
This problem is a nightmare, Big S from this forum has been an unbelievable help to date. Thank god for him because quiet frankly the backup service from Excitech has been non-existant. 9 emails no replies nothing. When i am ready for another CNC i will be looking elsewhere....
cheers
Beerman

[Eclipze]

Hi Beerman. You should only feel a "flex" in the ganty, but not movement. I've been machining a few acrylic parts this last couple of weeks, where I needed very tight tolerances. Most of the cuts have been within 0.05mm (0.002"). So I've paid particularly attention to tool bit flex and gantry flex. What I've typically found is there is significant flex in the gantry, when machining in the Y-Axis directions (gantry move up/down bed). I can see this flex just by leaning on the gantry, and have been thinking of installing a stiffer plate in the bottom section. The worst machining movement I get is with the gantry moving down to the rear, where I'II get a lot of chatter in this direction. I quite literally have to apply about a kilo of force on the spindle to stop it chattering. But it's the type of chattering where it built up in intensity over distance, undamped instablity. Haven't got to solving this, however I suspect it's the gantry flexing and hitting a harmonic.

But all this is for machining tolerances way under 2mm. Your problem sounds like it isn't machine flex. It's bearing movement. Feeding slowly is removing the peak load on the free play. I'd suspect if you applied hand pressure on the spindle, this feed in gouge would be vary (possibly reduce). You shoulding feel any movement in the spindle when you push on it in various direction, only minor flex. Grab the collet with one hand, and hold the gantry with the other. Push it around in all four directions to see if you can detect freeplay. Pocket a large square, and while it's machining, apply a bit of pressure to see how much influence you have on the cutting. You'll likely find the direction the free play occurs.

It's difficult to advise on where the problem is, but I'd suspect it's with the rails. As an example, look at the attached picture. There are set screws on the bearings which you should adjust to give slight pressure on the bearing. To take the freeplay out. It is best if you unbolt the ballscrew, and just wind it up to one end out of the way. They you can easily put the gantry back and forth down the rails, to feel how smooth it travels as you tighten the set screws. You don't want them too tight. But if they are loose, you'll get freeplay in the bearings.

[BEERMAN]

Eclipze
Thanks for the quick reply.
When i lower spindle to bottom of travel and grab top and bottom i get movement.
But i would call this flex right through the whole gantry. It is a probably 2mm but i do have to give it a fair push. Honestly after playing around with this for a month i am starting to doubt everything i do......damn you CNC damn you.
My machine has a aluminium cover over the gantry so i will have to remove it to get to adjustment for bearings. I think if i can't get adjustment i will replace them and see if i can remove any play.
Hopefully this is all it is.
There is no flex if i try and push sideways on the spindle in the x axis.
cheers
Beerman

[Eclipze]

Hahaa... just remember, once you get it sorted you'll be that much more confident

I had to remove the aluminium cover too in order to access those adjustments. Not the best of designs to get it off and service them. I almost drilled holes to make it easier next time.

You can probably see why I'm interested to install a plate across the gantry to reduce the flex now. Particularly a problem when feed through acrylic fast with a 12mm endmill.

[BEERMAN]

Eclipz
Just got the cover off and adjusted everything up it was all reasonably tight. Made bugger all difference, still flex right through. I really think it is flex in the whole gantry. Absolutely no movement x axis. Strange how the gouge only happens at the start of the plunge, even in MDF. I cut a series of test cuts
1. area clearance using raster
2. area clearance using spiral
3. 2d profiling on the inside of the line
Out of 6 only 2 were perfect. I can't find the problem and it is driving me to drink, no maybe not but it is frustrating.
I V carve nearly all my signs and no problem, may be due to the ramping action. That is why i thought it was in the DSP or programming.
But i got to fix it, if i do a area clearence 10mm deep into a timber sign for lettering the gouge occurs every time the tool enters a letter..looks terrible.
This problem has only just started occuring.
I don't know where to head next, but i think the gantry flex must have always been there and as i said the problem has only just occured, what do you reckon. If you stiffen yours up let me know how you go and i would do the same to mine.
I feel like my staffy dog, he sits there for hours chasing his tail. i haven't got a tail but i seem to be going round chasing something at the moment???????