And one more introduction...

@ Papa Athome,

first welcome here in the forum.

To your software tools and your comments:

WinPC-NC USB (full license)
So that you first have to work a little bit in there, I can fully understand, also own a Stepi 420 since 2017 and have so slowly the win at WinPC-NC but honestly, the best software I think there is for the Stepi ,
If you have reconfigured the z-axis, you should save yourself a profile with the changed parameter under Win PC-NC z.b. with the name "Z-axis reversal" so you can after a reboot of the software to reload this profile and your settings are as you have previously configured.
The positioning with the controls of the screen, you can really forget because I agree with you, so you really want to achieve something so you do not come around a handwheel.
I can only recommend that from WinPC-NC (Handwheel HR-10) (Link: https://www.lewetz.de/files/download/Handrad%20HR-10.pdf) I own it too and it improves the handling starting up and controlling the router by 100% !!

FreeCAD for 3D designs
The software is very good in my opinion, clearly learning to learn is also here.

Inscape for 2D designs
Well, I've never used it for the stepi.

The fact is simple, it requires practice practice practicing plunge depth, feed, etc. are all parameters with which you have to deal with, I know what I'm talking about, I thought there was a 3D printer with the router would be just as easy, but it is not, if you are not out of the area you will be overwhelmed with parameters that you did not know before or have dealt with.

Although there is much better software that does a lot of work, instead of first producing CAD then CAM software and then G-code, but that also has its price as Aspire 9 or Deskproto. Although it makes it easier because the programs directly create G-code, but still you still have to specify feed, speed of the router and puncture depth and I think that's the sticking point in the beginning. Exactly how which cutters I take for what, etc. But the best way to test something with materials and to be and then it works out sometime!

Greetings Reiner

I wish you a lot of success in any case!

@Reinard St.

Thanks for the welcome, it feels like I have made contact with the forum. 🙂

Good tip about the WinPC-USB to save it in a new configuration. I will follow up on that.

Same for the handwheel and that has a priority!
I noticed during my engraving test runs on marble that it is extremely important to:
a) have your surface *absolutely* level.
b) have an correct measurement on Z for that surface.

A short recap on my tests.
I tried to clamp down a marble tile (of 100 x 100 x 10 mm) and I thought it was level.
It was level within the measurement uncertenties of positioning/probing the four corners with the screen positioning tool, which is someting arount +/-0.2 mm?
Running my gcode for the engraving (at a depth of 0.1mm) the left side was not scratched at all and the right side showed some traces.

Thinking about it, the clamping might have bend the working surface of the 420 (I was not using any extra safety layer under the tile, no danger of drilling through) The tile was in the middle of the x-as and right at the front of the y-as. If bending is possible, this would be just the weak spot.

Next run I tried with a depth of 0.2 mm and I got an result. But it was more 'milling a trench' than 'engraving a line'.

If bending the bed by clamping force is in play then I have to come up with a method of checking and correcting it.
Doing probe measurements with the current screen controls is not accurate enough.
But keeping the z-ax fixed at Z and move to the four corners I can easely measure the height of the spindle holder above the working area within 0.01mm
Tightening or loosing up the clamp down bolts can than be used to level the surface.
That is what I want to try on my next run, which will be somewhere beginning next week.

This clamping down works with the marble tiles I have (left overs from a bathroom redecoration).
It will be interesting to see how this will work on glass.

In both cases, marble and glass, leveling the surface with a milling action before the engraving is not possible I think.

If everyting fails and I cannot come up with new ideas I will start asking questions in this forum. 🙂
Always good to know that some other people have already done/archieved what I want (which proves that it is possile) and are willing to share their experience. But the best way to learn is for myself putting one and one together and see if it works.

Kind regards,

Hello

I am not a specialist but the usual way to level things on a CNC is to generate a level surface relative to the tool. In the facts I usually take MDF and use the pocket function to surface an area greater than the part I want to work with. It is important to have all the surface machined in order to not leave any low spot. When this is done I am sure that the Z relative to the surface is always the same (within machining precision) and I can use this surface as a reference to clamp the part. I hope this will help you.

@voiliceo That does not make sense to me for glass. The surface is (locally) polished, ignoring bumbs and bends in the surface. Leveling it will demand re-polishing before the engraving.

If you are right then engraving glass with a stepcraft is not possible. Then I have to look for sand blasting or etching techniqes.

Kind regards.

I think I've seen an engraving bit with a spring loaded tip. That would solve some of the problems.

@ PapaAtHome

o to your project:

1st If the question arises me which table is installed in your Stepi 420?

Did you install the original table in the router?
The machine table consists of 8.0 mm high pressure laminate (HPL)
Or do you have the T-slot table made of aluminum?
The T-groove table is 4 mm thicker than the standard HPL worktop.

So the HPL plate is of course easily after you lay there as a tile on it and then only with 0.1mm Fräszustellung milling want.
There you will probably or evil not come around a T-slot table made of aluminum.

But now comes what has already voiliceo addressed.
I always do it that way, I span my aluminum T-slot table then a MDF or even multi-ply wood panel.
This is then milled plan by my router. So that I first have a flat surface, yes because the T-slot table is not 100% flat.

Then I can lay on the plan milled surface of MDF or multilayer my work, in your case, the tile and you will see, the workpiece is now plan on and even with 0,1mm milling, the tile is scratched everywhere, because you now one Have plane surface to the spindle.

I would not adjust the spindle in the neck up, because you then have the spindle then no longer 100% angle sitting !!!!

So first, the spindle completely in the spindle mount again until it stops. (It must be fixed and straight, possibly a NEN bolt in the spindle and check with the angle from the table if the bolt is at an angle !!)

Then lay MDF or multi-layer board on the work table and fix, mill plan and then put your tile on the MDF or multi-layer board and you're ready to go !!

Kind regards.

@Reiner St.
I do not have a T-groove table base (yet).
On top of the HPL base I have an MDF plate (499 x 314 x 20mm, max size for the 420) with double sided tape.
It does not move and I have not noticed any bending (but it is also time consuming to remove it from the 8mm HPL base).
Any target I just screw on top of it, there is no room to spare for using the clamp bars that came with the stepi.
(I need to check if 8 or 12mm MDF will allow me to use the clamp bars)

For engraving the marble tiles I wanted to use the clamp bars. (I could have used double sided tape or made some wooden bars for screwing but decided to remove the 20mm MDF base. Then I was left with only the HPL base which was not my best choice.
(I do agree with a quote I've seen on the forum before: any problem, never mind how simple, will become more complicated when you add some thinking)

Buying the 420 was some investment for me and I did not included any extras, except for the WinPC-USB licence and a tool measuerement switch.
I wanted to get some hands on experience first before deciding on what extra parts to buy (including an appropriate spindle).
The aluminium T-slot sounds more rigid than the HPL 8mm plate, a good thing to go for.
Putting MDF (8 or 12mm) on top of that sounds logic to me.
Leveling the MDF did not came up with me, thanks for the tip, that is usefull.

More on the spindle (and my original plan of taking measurements).
Currently I use a cheap proxon look alike. It behaves nicely for its price but will break in the long run. It is not made for milling but for hand-held actons.
I had an adaptor made for my current spindle. It sits tight and does not move.
It is not the spindle I want to use in future. I just need to get the spare money to get a decent one, the ones I looked for don't come cheap.

The idea I had on taking measurements is keeping the z-axis fixed and only more in the xy-plane.
Then taking measurements with an electonic caliper from the orange plate (holding the spindle) to the top of the working surface is easy done and without the need for z-axis movement.
This way I can check if the surface is level within the tolerance of my caliper and xy-movement induced z-differences.
When I know that the surface is level within limits I also know at which height that will be. Setting Z0 for that height is not too dificult.

So, outlining my next test with engraving marble will include the following steps.
1) Put in the 20mm MDF base again (using double sided tape).
2) Level the surface.
2b) Just to see that my idea works: measurement check that it is level.
3) Put in the marble tile. (Holding it in place with double sided tape, a made-do-size clamp with screws or both).
3b) Take measurements to check that the top of the mable tile is level within 0.1mm, adjust if required.
4) Set the appropriate Z0 value.
5) Do the engraving.

I see if I can make photo's to show what I do.

Kind regards.

@ PapaAtHome

Maybe I have something for you.
I also have a Kress 800 FME milling spindle and a MM-1000 (EU) milling spindle, which I really do not need anymore because I switched to an AMB Milling Motor 1050 FME-P DI with external speed control for the D series.

If you are interested, then get in touch.
Would the Kress 800 FME including 1 set carbon brushes for 120, - Euro Sell. (bought 05.04.2017)
The MM 1000 (EU) for 220, - Euro (bought on 20.06.2018)
Both machines have a maximum running time of 50 hours, because I'm a mechanic and almost only come at the weekend for milling.
Can also send the original invoice as a copy then.
I also have various collets and union nuts in different sizes !!
Or give me a price suggestion, what you would be willing to pay, maybe we can agree!?

As I said, if interested and unfortunately for this hobby always expensive money for these machines get in touch.
Can not tell you how high the shipping costs are, because I have to pack the right spindle and weigh it on the post!

Regards Reiner

P.S. Your approach to the next test with Gravurmarmor looks good. Of course, it now depends on whether the Gravurmarmor on the surface is even, smooth.
I am looking forward to your test and pictures!

I promised to publish some pictures.
Have al look at https://www.stepcraft-systems.com/en/forum/show-us-your-stepcraft-creations/6015-look-what-i-have-learned