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Rostock plywood SCAD dxf for laser cutting

by RustyPaint, published

Rostock plywood SCAD dxf for laser cutting by RustyPaint Oct 2, 2012

Description

I took Nudel_P scad file and modified it for use with laser cutting acrylic with holes for a mk1 pcb heatbed, printrboard, and l-brackets for the corner support. A notch was made in the corner for running wires from the top switches down to the base.

Images shown still have the protective paper on them.

l-brackets are from here:
thingiverse.com/thing:2226

Marking this work in progress until it is fully built.

UPDATE 10-20-2012:
It is up and running (no longer in progress). Ended up using particle board for the side pieces for extra stability from added weight. The acrylic was too flimsy.

Recent Comments

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350mm/s with 20 tooth pulleys, this is close to my upper limit before I start getting skipping. Another thing to check is you current limiters on your stepper controllers (the trim pots). There is a bit of a black art to getting them adjusted correctly. Too much and things get to hot and you get skipping, too little and your torque goes down and you get skipping. If you are getting skipping where the head does not line up with the next layer, that can be your issue. Also, stutter can be from your serial link. Try loading the gcode on a sd card and run the printer from there. If you look at the gcodes for Marlin, there are instructions on how to do that.
thanks for getting back to me. I'm running at 45mm/s with 150mm/s travel. I'm using 40 tooth pulleys, what speeds are you running?
I'm running the default. If your travel speed is too fast it can cause jerky movements as well especially if you are running 20 teeth pulleys since the Atmel cannot feed the pulse to the stepper controller fast enough with fine stepping.

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Instructions

Send one of each (top and base) to a laser cutter (using mm for units) and assemble.

scad is documented if you need to adjust for different electronics ect.
Same scad file is used to create the top and base. A switch is used at the top of the file to indicate type.
what distance are the top and bottom spaced apart by?
This is dependant on the length of your belts you get. Rostock technically has no height limit. Mine is about 2.5 ft with 850 teeth GT2 belts since the 792 were not available at the time of order.
I have the 792 teeth GT2 belts any way to figure out how far a part I should space my motor ends and idler ends? Also I am using a printrboard rev B for my electronics, where can I get Marlin for Rostock that will compile for the printrboard?
You just push up the idlers until you get good tension on the belts (they sound like a bass guitar when you strum them) and that is the proper length. I just put my toes on the base, pull up with my hand, and tightened down the bolts with the other hand.

I haven't updated my firmware in a while, but what I understand, Marlin has delta and Printrboard in the main branch.

Otherwise, use Johann's branch:
https://github.com/jcrocholl/Marlin
Install Teensyduino:
http://www.pjrc.com/teensy/td_download.html
Build with Teensy++ 2.0
Load the image to the board with FLIP:
http://www.atmel.com/tools/FLIP.aspx
Look at "DFU BOOTLOADER" on here:
http://reprap.org/wiki/Printrboard#Loading_Firmware_.28Windows.29
Thanks for getting back! So everything I need should be in the main branch of Marlin? If so that makes everything easier. I just finished installing the belts and tensioning them then attaching the carriages to the belts. Should the platform be hard to move? Or is my setup too tight?
The man Marlin branch does have the delta code. Johann explains in this post:
https://groups.google.com/d/msg/deltabot/JyS_EQ6phWQ/mOSP-Y6sjuwJ

The platform should take some effort to move when connected to the steppers. You will also need to "exercise" your universal joints to break them in. Have the bot move on it's X and Y axis to do this.
thanks again! As far as entering in the data for the Delta section are the default numerical constants for the Rostock design or are they for another printer or arbitrary? I built my Rostock using your DXFs, traxxas universal joint rod ends, and the same rods/belts Johan used on his prototype. Is there a guide for finding these constants for delta/rostock printers?
I'm using these arms:
http://www.thingiverse.com/thing:17917
That are 250mm from hole to hole.

So my settings look like this for the "old" Rostock:
#define DELTA_DIAGONAL_ROD 250.0 // mm
#define DELTA_SMOOTH_ROD_OFFSET 175.0 // mm
#define DELTA_EFFECTOR_OFFSET 33.0 // mm
#define DELTA_CARRIAGE_OFFSET 18.0 // mm

End stops are connected like this (along with steppers):
http://reprap.org/wiki/Rostock#Assembly
(see picture on the right)

Just connect to what is printed on the PCB as far as the steppers and the endstops to what is shown in the picture.

It looks like Johann's branch of Marlin is already preconfigured for PrintrBoard.
I'm using these arms:
http://www.thingiverse.com/thing:17917
That are 250mm from hole to hole.

So my settings look like this for the "old" Rostock:
#define DELTA_DIAGONAL_ROD 250.0 // mm
#define DELTA_SMOOTH_ROD_OFFSET 175.0 // mm
#define DELTA_EFFECTOR_OFFSET 33.0 // mm
#define DELTA_CARRIAGE_OFFSET 18.0 // mm

End stops are connected like this (along with steppers):
http://reprap.org/wiki/Rostock#Assembly
(see picture on the right)

Just connect to what is printed on the PCB as far as the steppers and the endstops to what is shown in the picture.

It looks like Johann's branch of Marlin is already preconfigured for PrintrBoard.
Thanks for all your help so far! I did some tests earlier with a friend and we found that there isn't a definitive guide for configuring the firmware for the Delta platform. We set his up (I have yet to find my USB micro cable so I havent tested my printrboard firmware) with his RAMPS setup and only the "Z" axis began to move during the homing routine, is there anything else we need to do aside form the delta kinematics section inside the main config or elsewhere?
Try homing with just G28
I will when I get to the hackerspace this week. Now as far as enabling delta kinematics its I just have to edit the configuration.h right? I want to make sure we have everything configured correctly before attempting to home and calibrate again. If you could post your configuration.h for your build of marlin for your rostock that would make things so much easier. Thanks for answering all my novice questions, its been very helpful!
How do you have your endstops configured in the configuration.h file for printrboard? The RAMPS shield has min and max endstop ports what is the printrboard setup like? If you could sent me your configuration.h that would be helpful, I'm so close to having this thing working now!
My configuration file is for an older Marlin. My rostock just went out of calibration, so I might try updating while I'm at it. I'll try to post something here if I find something that is "odd" about the setup.
I got everything working now! But it can be a bit jerky and stutter, I heard this could be caused by the amount of DELTA_SEGMENTS_PER_SECOND being too high for the processor to compute. The defaul is 200, what are you using for printrboard?
I'm running the default. If your travel speed is too fast it can cause jerky movements as well especially if you are running 20 teeth pulleys since the Atmel cannot feed the pulse to the stepper controller fast enough with fine stepping.
thanks for getting back to me. I'm running at 45mm/s with 150mm/s travel. I'm using 40 tooth pulleys, what speeds are you running?
350mm/s with 20 tooth pulleys, this is close to my upper limit before I start getting skipping. Another thing to check is you current limiters on your stepper controllers (the trim pots). There is a bit of a black art to getting them adjusted correctly. Too much and things get to hot and you get skipping, too little and your torque goes down and you get skipping. If you are getting skipping where the head does not line up with the next layer, that can be your issue. Also, stutter can be from your serial link. Try loading the gcode on a sd card and run the printer from there. If you look at the gcodes for Marlin, there are instructions on how to do that.
How is the strength of the acrylic vs wood/MDF ? I started making mine out of MDF (1/2 in) using a laser to etch your stencil onto the MDF. It doesn't seem that its going to be very accurate so I am considering using some acrylic I have collected over the last few months for my base and top. I need to know if the acrylic is going to be sturdy enough before I use my stock.
As long as the base you put it on is nice and level. It will get its strength from the surface that it is sitting on due to the weight. Care has to be taken when mounting the side pieces since that will in part determine how level it will be. I ended up shimming the feet of the rostock with cardstock until the linear sides were level using a bubble level. My parts are much more true after leveling.
How come the print bed is not centered between all three axis?
If you draw a parallel line to the axis at the center of each axis, the intersection point will be at the center of the heat bead.
Take a look at: thingiverse.com/thing:27573
cool thanks! How high is it mounted? What if I don't plan to use a heated bed but isntead want a platform where I want a 1/8" aluminumt plate with glass attached to it where it will be covered in painters tape before printing. how tall should I make it?
The height of the heat bed is not critical for operation since you can adjust the Z length of the printable area in the Marlin firmware.
Take a look at: reprap.org/wiki/Rostock#How_do_you_adjust_the_height_of_the_print_surface.3F
How Thick is the Acrylic that you are using?
Mine measures out to be about 5.35mm. It was what the laser cutter service provided. It does flex slightly so you must let the rostock sit on a solid flat surface. I ended up shimming up the corners to where the vertical rods are level with a bubble level. This seems to produce good results.
Hi Rusty,

Thanks for the great job. I take it this setup allows for a 20mm*20mm / 8"x8" build area.

I am looking for a way out for those of us without access to a laser cutter. Is there any way to convert the base and top dxf files to "life-size" (multipage A4) pdf files? With those pdf's we would be able to use the (taped together) A4's as a 'glue-on' template for cutting and drilling.

Thanks in advance for thinking this over,

Hendrik
This is the "standard" Rostock layout.  IE, this gives you an approximate 9 inch circle of printable area.  Basically you can print every where on the print bed except the corners.

As far as printing them out, I used a DXF to PDF converter and used the "poster print" option of the PDF view and taped the 4 pages together to test the layout before I had it sent to a laser cutter.

The program I used was Acme DWG Converter.  Use Batch Convert -> Batch transform by scale.
Rusty,

Thanks for the quick reply. I'll give it a try.

Regards,

Hendrik
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