Category: CNC-en

In this post, you can see how I changed the original Indymill to more rigidity by using the original 1605 aluminium nut holders for the 1605 ball bearing screws of the Y axis, and how I made use of the BK12 and BF12 ball bearing blocks instead of the 3d printed parts like in the original build.

When building the frame, make sure that you do not initially screw anything tight.  Follow the steps that apply to any build:

1. Make the footprint square by measuring either with a good 90 degrees angled measuring hook OR measure the diagonals against each other and make them alike.  Then, tighten all corner screws .
2. Re-measure the footprint’s left against right length and also front/rear length. If there is any difference here,  a) take everything apart and b) make sure you have equal sizes for your build where this is required.  OR, if you have a non-standard build, make sure you build according to specs sizes. The, do 1. again.
3. For a lineair rail: use a ruler that is specifically made for your type of rail  You can 3d print one or buy two aluminium ones.  ALWAYS use at least 2 rulers!  With the rulers in place at 20% from left and 20% from the right,  after you have installed the rail loosely with the screw in the nuts, tighten the screw a bit but not too stiff..  We will get back to these screws at a later stage.
4. Put the connecting piece on the motor’s axle (8mm side) and tighten this well.  Preferably, use some loctite on the axle but don’t overdo it.  Be aware that you need to testfit the BK12 first.  make sure that the connecting piece almost touches the BK12’s nut!
5. Put the stepper motor and the BK12 connector together, using the 3d printed thin NEMA23 adapter plate between motor and steel plate. Do not yet tighten this too much.
6. Make an original aluminium 1605 nut holder block shorter to fit exactly.  See the picture.
7. Fit the aluminium nut holder block including the entire assembly of the 600 mm long 1605 ball bearing screw on the machine, and superglue the block in the correct position.  Let it dry so it won/t come off. Demount verything except the steel sideplate and the glued aluminium nut holder.
8. clamp the nut holder to the steel plate with a grip vice, just to make sure it all keeps together.
9. Drill 3 new 4mm holes through the steel plate’s lower part ,  drill through the aluminium block as far as possible.  2 holes on the lower side and 1 just between 2 of the top 3 holes,  NOT where the existing hole of the aluminium nut holder block exists.
10. Get the nut holder block loose, if it has not already come off.
11. Tap M5 in the holes of the nut holder block.  You will have come through the big center hole (for the nut) with 2 holes, make sure this gets cleaned up on the inside.
12. Drill the new holes in the sideplates with 5.5 mm drill (to give you mounting clearance)
13. Place the sideplate on the 2 bearing blocks of the linear rail with 4 outer M3 x8 (or x10) screws.
14. Put everything loosely together
15. Mill an end baring block to fit the 1605 ‘s screw end at the front an mount this at the exact center of the small front plate.
16. Now, connect your nema 23 engine to a motor steering device so you can test the setup.  First, turn the screw by hand and it should run smooth.
17. Since you want to have an even height of the side plates, do not alter these unless it needs to be done on both sides equally.
18. Your fixation point is the only non-movable position, at the rear of the frame.
19. Move the carriage to the rear and now, see if you have slack on the M3 screws of the slide bearings AND on of the 3x M5 screw the rear of the aluminium nut holder. If so, first tighten the M3 screws.  Then tighten the M5 screws.  If not, loosen ALL of the linear rails screws ans move the rail a little. If this is possible, tighten the M3 screws of the linear rail’s bearing blocks.  Then, try to get as much clearance on the linear rail’s movement up/down as you can and tighten the 3x M5 screws of the nut holder block.
20. Now, tighten 1 screw only of the linear rail, at the position above the nut holder.
21. Move the carriage entirely forward position.
22. Tighten the linear rail’s M3 screw that is exactly in position above the nut holder (of the ball bearing screw)
23. Now, tighten all screws of the linear rail.
24. You’re done!
25. Check the other side and if the linear rail’s height differs from the other side,  the only thing to do is to start over again, where your slack is in the 5.5 mm holes of the steel plate’s screw holes for the  nut block.  If you play with this, and then adjust the linear rail’s height, you can get it all even.  At least’eventually I got mine right but it took some time.  Have fun!

Things to bear in mind: You don’t want anything out of parallel like a linear rail that is uneven to the aluminium profile on which it is mounted or a ball bearing screw that gets under tension.  There is also another way to see what is happening while you are tweaking the hardware/frame: take the front bearing off and see what happens to the end of your ball bearing screw in the hole up front when you move the carriage.  It can tell you much about what is happening…  It should always stay perfectly centered but I’ve seen it up, down and all other directions.. -)

And- I must say, this build goes quite well. The materials are OK, and the guideline from the build description was very good. Although I never use it anymore.  The build is quite self-explanatory once you start building the Indymill CNC machine.  I also cahnged quite some parts, and made alterations where I felt this would improve the machine to fit my purpose better.

The Indymill’s Z-axis uses a lead screw  by design , and not a ballscrew as I would like.  But- that will be changed later.

For now, the lead screw solution will be OK because I will first build the Indymill machine and use the 500 Watt DC engine I already have for my CNC3018 setup.

The leadscrew of the Indymill is an 8mm leadscrew with a brass nut mounted in a 3d printed part that is mounted on the vertical rear of the Z-plate.

And- the drive stepper motor is mounted hanging on a horizontal plate on top of the Z-plate.

The required motion is exchanged to the leadscrew with a pair of 8x10x22  treehed wheels that are coupled with a GT2-10 mm wide 200 mm long belt.

The change I made to the original setup is to use an original 8mm lead screw bearing on top, under the horizontal plate.

I did not particularly like the original setup with an 8mm bearing in a 3d printed holder, and an 8 mm lockup ring under and above this bearing.

I had to machine the pro-bearing to fit the Indymill’s mounting holes and get  the threaded drive screw nicely centered.

After configuring the reprap Mellow FLY-CDY-V2 motherboard for CNC including the webinterface and installing Mellow’s TMC2209 driver units I got  sensorless homing setup for the Indymill.

It took a lot of time to get it all tuned, as the 3 axes act entirely different due to their different inertia.  The weight that is carried is obviously higher for the Y- than for the X axis.  And the 4 kilogram weighing spindle engine made it pretty difficult to get the Z axis tuned.

The resulting config file is provided in this post.  Use this with caution, since every machine is different, and the used stepper motors, cabling, steppers and PSU all have influence on the CNC’s behaviour and thus on the config settings.

To have the original Mellow FLY TMC2209 drivers work with sensorless homing, set the underneath dip switch to ON

(Diag pin will then be connected).  It took me some time to find out that this is different than other TMC2209 drivers, where the Diag pin is activated by jumper settings on the motherboard.  No idea what happens when you use non-Fly TMC2209’s on the Fly board, but I expect this will not work for sensorless homing.

What I experience on the Y axis is that if you have real problems with homing or skipping steps, the steel Y carriage plates may bend and cause a non-square Y carriage that will never align any more.  I repaired this but preventing is better.

GO TO THE INDYMILL & Reprap Driver POST 

Since this setup with sensorless homing never gave me good speed ratings, I disassembled this setup and continued with endstop setup.  If you want to know how to setup sensorless homing with reprap, please look at my sensorless homing setup on my dual carriage 3d printer, where this works perfect!

This is my test setup for a 1.4 RAMPS shield on top of an Arduino Mega with TMC2209 drivers, optical endstops and individually homing of dual Yaxes PLUS an LCD that shows the exact XYZ locations anytime.

Firstly, I must admit that this option was initially NOT on my list bacause I felt this was a pure hobby-like option.  BUT- as my requirements list grew and other options got less and less, I ordered a Ramps 1.6 shield and plugged one of my Mega2560 boards under it.  Then- the search began to get a working fork of GRBL for arduino that both accomodated the Mega 2560 and my requirements list.  On this list: GRBL, Squaring my gantry, LCD with useful data, Handwheel connection, Preconfigurable buttons on the handwheel (stop, define as zero, probe here, et cetera).  The fork that does this all is: GRBL-Mega-edge.  The last comment is of April, 2020 and the fork was updated last in 2019.  But- it works straight out of the box and the documentation is very well maintained. 

Since it works under the Arduino IDE and has its own library, I foresee little problems in the future.  Everything is freely configurable and it might even be possible to put an Arduino Due in place of the Mega2560 in this setup, with some tweaking of pins and speeds.    And- tweaking is required for the hardware as well. The Ramps boards were never designed for 24 Volts, so this needs to be taken care of.  One might of course use 12 Volts and use external driver modules, but I intend to keep everything very small and make use of an external PSU, and a small handwheel-like box for the Mega2560, Ramps, drivers, LCD, buttons and handwheel knob.  By the way: For getting my designs I already had from my 3d printer background towards the CNC I bought Estlcam (CAM program). This really does a great job at converting it to Gcode and sending it to my Grbl- Mega 2560/RAMPS setup.

Afterthoughts 2021-06-22:  When connecting Estlcam to the Mega2560 and RAMPS1.6 shield, Estlcam can program the RAMPS / Mega2560 configuration, including dual X and Y axis.  This works straight out of the box including endstops. Actually this is easier than first compiling GRBL on RAMPS with Arduino’s compiler.  BUT- it seems that autosquaring does either not work or I did not install Estlcam’s options correctly since the endstops on the dual axis appear to function in parallel instead of indicvidually per axle.

24 Volts connecting is not possible on a RAMPS shield just like that. I removed D1 and powered the Mega2560 with a 9 Volts PSU, and the shield seperately with 24 Volts.  For the Arduino DUE, dedicated RAMPS boards are already available (Smart ramps that compensates for the 3.3 volts in/out Voltage of the Arduino Due)!.

Another option for Estlcam is to program the Mega2560 without RAMPS shield and connect everything directly to the Mega2560 with jumpers.  If this is done, Estlcam will do the bare programming of the Mega and Estlcam can steer almost everything.  Since I bought a license for Estlcam I will, at a later stage, try this as well.  SEE THIS POST