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Rostock Prisma

by JorgeRdgz, published

Rostock Prisma by JorgeRdgz Nov 9, 2012
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A derivative of Johann's Rostock but using 80/20 1010 T-Slotted aluminum instead of smooth SS rods. The extruded aluminum provide support for the prism structure.

Video: http://youtu.be/STc54aOQdK4

The goal for my derivative of the Johann’s Rostock was to build a simpler, lighter and more robust structure. I decided to use extruded aluminum since it’s quite strong, readily available, and relatively inexpensive. A piece of 80/20 10 SERIES 1010 1" X 1" T-SLOTTED EXTRUSION x 72" (1828.8mm) sells for $19 in Amazon.com. I was also inclined to use aluminum given that I have previous experience building and fabricating with this material (I built an all aluminum airplane in my garage).

Gone are all the wood parts, and the stainless steel rods. I kept the idea of using as many 3D printed parts as possible, since I had easy access to a friend’s Prusa Mendel printer. I am a software developer; hence it was easy for me to learn OpenSCAD to design my own parts. I tried to keep the number of new parts to a minimum and, if possible, reuse or make a derivative of the original Rostock parts.

I studied the Rostock Max by SeeMeCNC, which I think it is awesome. I love the “Cheapskate” design so I tried to replicate it but instead of flat plates for the carriage I decided to modify Johann’s design to fit the profile of the 1010 and to accommodate four 608 bearings. After multiple iterations and head scratching sessions, I concluded that the best and easiest way to provide anti-backlash pressure between the bearings and the channel was to elongate the shaft holes and wrap a rubber band between the opposing M4 bolts serving as bearing shafts. It works beautifully.

Another difference is in the track of the GT2 belt. On the Max, the belt in the back of the carriage tracks within the 1010 slot. On the other side of the carriage, the belt tracks a few millimeters parallel to the 1010 beam. On the PRISMA, the whole length of the belt, up and down segments, track within the inward facing slot of the 1010 beam. There’s a separation of approximately 3mm between the up and down moving segments of the belt. The separation is made possible by the double bearing idler design. One bearing pushes one segment of the belt inward into the channel while the other keeps the top belt tracking just above and flush with the edges of the channel. The only drawback to this approach was that it requires you to widen 1.5” (38mm) of the channel at the top and bottom to allow the 608 bearing to fit inside the slot in order to push the belt farther in. You can easily accomplish this task with a Dremel rotary tool, metal cutting tool, small sanding tool and a flat screwdriver.

The three vertical sections of 1010 extrusion provide the support for the entire structure. I used my cheap compound miter saw with a $12 metal cutting blade to cut the extruded aluminum pieces. I cut the vertical pieces to 36” ( 914.4mm). This translates to a maximum build height of roughly 13” (330mm). You can increase the build height by using longer verticals, however you need to keep in mind that you will need longer GT2 belts.

The horizontal aluminum pieces are sandwiched in between top and bottom plastic corner gussets at each end and secured with t-nuts. You can buy 80/20 t-nuts at $0.24 a piece or you can make your own by printing a bunch or tnut.stl copies and super gluing a regular 10-32 nut to the plastic. The final structure is a triangular/prism beam very straight, clean and sturdy.

Lastly, all other parts hang from the aluminum extrusion; motor mounts, heated bed, idlers, electronics, power supply, etc. I design and printed special mounting clips that fit the 1010 profile.


Since some of you ask, here is an initial BOM. Remember this is still WIP. Some items in the list might (and probably will) change. I will be making minor mods to the carriage, bearing clip, and extruder parts. More instructions, files and pictures will be added soon.

Bill of Material
Qty Description Source
3 80/20 10 SERIES 1010 1" X 1" T-SLOTTED EXTRUSION x 914.4mm (36") www.Amazon.com
9 80/20 10 SERIES 1010 1" X 1" T-SLOTTED EXTRUSION x 274.32mm (10.8") www.Amazon.com
1 213mm x 213mm x 1.6mm (8.4" x 8.4" x 0.063") Aluminum Sheet www.onlinemetals.com
Hardware and Misc. Parts
6 4.8mm OD Carbon Fiber tubes 220mm length Local Hobby Store
36 608ZZ 8x22x7 Shielded Greased Miniature Ball Bearings www.UltiMachine.com
12 18-8 Stainless Steel Socket Head Cap Screw, M3 Thread, 22MM Length www.mcmaster.com
40 18-8 Stainless Steel Socket Head Cap Screw, M3 Thread, 10MM Length www.mcmaster.com
6 18-8 Stainless Steel Socket Head Cap Screw, M4 Thread, 60MM Length www.mcmaster.com
24 18-8 Stainless Steel Socket Head Cap Screw, M4 Thread, 45MM Length www.mcmaster.com
6 18-8 Stainless Steel Socket Head Cap Screw, M4 Thread, 25MM Length www.mcmaster.com
52 18-8 Stainless Steel Nylon-Insert Hex Locknut, M3 Size www.mcmaster.com
36 18-8 Stainless Steel Nylon-Insert Hex Locknut, M4 Size www.mcmaster.com
52 18-8 Stainless Steel Flat Washer, M3 Screw Size www.mcmaster.com
36 18-8 Stainless Steel Flat Washer, M4 Screw Size www.mcmaster.com
108 18-8 Stainless Steel Button Head Screw, 10-32 Thread, 0.5" Length www.mcmaster.com
108 18-8 Stainless Steel Machine Screw Hex Nut, 10-32 Thread www.mcmaster.com
108 18-8 Stainless Steel General Purpose Washers, Size 10 screw www.mcmaster.com
1 RAMPS Pre-Assembled Kit Complete www.UltiMachine.com
1 PCB Heatbed MK2 www.Ebay.com
4 Kysan 1124090 Nema 17 Stepper Motor www.UltiMachine.com
Belts and Pulleys
18ft Timing Belt, GT2, Custom Length www.UltiMachine.com
3 Timing Pulley, GT2, 20 Tooth www.UltiMachine.com
1 Hot-End Assembly for "Steves-Extruder" www.SeeMeCNC.com
2 Rotating Polybutylene Tube Fitting, Adapter for 4MM Tube OD, M5 X 0.8 Male Pipe Thread www.mcmaster.com
5ft Super-Smooth Clear Mfa Tubing, 2 mm ID, 4 mm OD, 1 mm Wall Thickness www.mcmaster.com
Printed Parts
80 tnut.stl www.thingiverse.com/thing:34146
3 carriage_06a.stl www.thingiverse.com/thing:34146
3 carriage_06b.stl www.thingiverse.com/thing:34146
24 carriageAxle.stl www.thingiverse.com/thing:34146
15 corner_gusset.stl www.thingiverse.com/thing:34146
3 corner_gusset_belt_notch.stl www.thingiverse.com/thing:34146
3 motor_end.stl www.thingiverse.com/thing:34146
6 motorEndClip.stl www.thingiverse.com/thing:34146
12 idlerClip.stl www.thingiverse.com/thing:34146
24 bearingbushing_long.stl www.thingiverse.com/thing:34146
4 hot_bed_clip.stl http://www.thingiverse.com/thing:34146
1 Airtripper's Bowden Extruder (modified to accept 4mm tube fitting) www.thingiverse.com/thing:22426
12 jaws.stl www.thingiverse.com/thing:17175
12 joint.stl www.thingiverse.com/thing:17175

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Comments deleted.

To those of you who have built this thing:

Do I need 3 end stops for this? I've never built a delta printer before and without build instructions it's a bit rough.
How do you get everything set level?

Yes you need 3 end stops for a delta -- For full instructions on building a delta style printer see http://www.appropedia.org/Delta_Build_Overview:MOST

Thanks man, that's going to be huge.

Man...how did I miss this project when I started working on this?

I like the look you have going. Mine seems like it uses too much printed parts. I need to find a way to reduce print time, and material cost. I really like your top and bottom vertexeseses. pretty and slim....but that roller vertical guide carriage looks like it takes a week to print for each one. There has got to be a way to reduce the printed part content in there,,,, I also like the belt in the extrusion idea, it keeps the max build area and it makes the downward belt force more fully down. But I am too lazy to cut that hole once, much less 3x's. I was just going to make my horizontal extrusions a little longer to make up for it, but I might need to think about that.

Great stuff man.

1 inch t-slot extrusion scale up of kossel mini
by grb352

For anyone in the UK/Eu that's havng trouble sourcing the t-slot rods for this model, take a look at the 'Cherry Pi'. It uses standard Bosch/Rexroth aluminium extrusion which is very cheap, and fairly common in Europe. There's a UK supplier called 'KJN Aluminium Profile' that stocks these. I've priced up the entire frame cost to be under £20.

This variant looks great - nice work Jorge, seriously. Delta's seem to be such a better design. I recently built an i3 and am now kicking myself that I didn't go for a delta, so have been looking at the cheapest way to reuse my RAMPS electronics, and build a decent delta without spending several hundred more in parts.

Out of interest, could you tell me if you think it would be possible to:

A) Slightly reduce the height
B) Make the area under the build platform smaller, and move the motors so they are basically lower down and attached inside the lower frame, instead of above it? My thinking is that you could compact the space needed for the electronics. A bit like the 3DR where it's all housed in a pretty small area.

Jorge, Now that you have had this machine for a while I wonder how you like it? I have a ultimaker and wonder if this should be my next machine?

cool thing + that is the most coolest thing I've ever seen in my life

Just making this right now... it seems like I only need 25 bearings. Is there any more detailed build instructions?

Got my aluminum extrusion today. The parts as printed are at least 1mm to small for the aluminum... not sure what i'm going to do now...

So I filed all the carriages down... They fit now. It seems like they each use 8 bearings instead of 4 in case anyone else is building one of these.

Hey Jorge how long are your carbon arms from center to center.

The BOM mentions 220mm, I assume they go onto the printer at that length (without being cut)

I'll second that...
Though a Scaled model is probably wiser, I would still like to hear the maker's opinion.

Hey guys! I´m from Europe and thats my problem xD
The aluminum frame is 1 inch x 1 inch. (2,54 cm x 2,54 cm)... but I can only get 2,50 cm x 2,50 cm. So what would be the best move? Should I scale it down to 98,4% so that the printed parts fit to my 2,50 cm aluminum? What problems can I expect for the other parts?
Perhaps I should print all at 100% and fill the difference? What about the moving parts? Did everyone build the Rostock Prisma in Europe? Some help would be awesome! thx maxtex

I don't think scaling down the stl will work since everything will scale down and that will cause problems with other parts fitting correctly. I would recommend printing 100% and filling the difference. For the moving carriage parts try using teflon tape to fill the gaps.

Hey Jorge, I designed the parts myself to fit 100%. I will use a spectra line and my steppers will be on the top. If I finished my printer I will upload these files as a derivate of yours. I'm thinking of "Rostock Prisma Euro-Version"... your printer was quite inspiring to me =)

Has anyone consider adapting this design to mount a UV light or DIY laser instead of an extruder? Then, you could shoot the beam into your vat of resin and get some really accurate prints. The resin would sit in an open top vat at the bottom and you would elongate the machine to sit above the vat. Any thoughts?

I love it looks awesome!

First, I love the clean look of the rails/belts. Id love to get deeper into this but Im still trying to get my first build of anything done... Here is where I will fire my questions...

  1. Why is it the bearings are ALWAYS sitting on the teeth of the belt. I would think that a direction or routing with the flat back of the belt would be 'smoother'.

  2. Your brackets for mounting your bearings. You mentioned them digging into the channel (the bearing). Have you considered the same design but elongating the part of the bracket sitting against the rail and having the hole for the shaft at the outer most part so the bearing is sitting outward a bit farther?

As for your rubber bands... very ingenious. Have you considered some form of spring to maintain tension?

Has anyone created build instructions, or could post some measurements on the build? Where do you cut the 80/20 for belt insertion? How far from the floor to the first triangle frame? A technical drawing or cad drawing posted would speed up the build process and eliminate all guesswork.

I'm currently building another Rostock derivation for a CNC mill, and Iwas was wondering how your pulley system works for the linear motion of the arms?

The 80/20 10 Series is a T slotted aluminum extrusion. Each slot (channel) is approx. 6mm deep by 6mm wide. I wanted to keep the printer clean so the channel looked like the perfect place to hide the GT2 belt. On the PRISMA the vertical extrusion serves as the carriage beam and the leg of the printer. This presented a problem if I were to route the GT2 belt up and around the carriage beam through the back and inner channels. Therefore I decided to route the belt through the inner channel only (the one facing the heat bed). In this configuration I have 2 pieces of the belt riding in the same channel. Hence, I needed a way to create separation between the 2 pieces. That is the purpose of the the double bearing idler. The first bearings pushes the inner side of the belt deep into the channel while the second bearing keeps the outer side of the belt riding flush with the edges of the channel. Important caveat however, since the 608ZZ bearing is slightly wider than the width of the mouth of the channel you will need to widen the channel edges so that the bearing clears the edges and is able to push the inner belt deep into the channel. Also note that you need 2 idlers, top and bottom, for each belt. Hope this helps. Happy building.

Printer looks great and Im halfway through printing all the parts but I just niticed that motor_end.stl is missing, can you upload it please? Thank you!

Done! Thanks for pointing this out. Good luck with your build.

Thanks for uploading the motor_end. I do have an additional question,
you cant see it in the picture but in the video it looks like you have
something mounted on the back of the upper carriages. On the ones I
printed there is a raised area in the center of the back of each, can you explain what that is for or what is on the back of the upper cariage in the video. Thanks

At the top of the printer, attached to the bottom of each one of the idlers is a small microswitch, the mechanical end stops. The printer uses them for calculating the Home position. I used 3M double sided tape to hold them in place. The raised area on the back of the top carriage has a small hole at the top that is meant for a 10mm M3 screw. Just screw the M3 into the hole and it will self tap. When you issue the Home command the carriage moves up and stops when the head of the screw hits the microswitch. You use the screw to make fine adjustments during calibration. If when you Home your printer for the first time, the carriages move down instead of up, you will need to change a setting in the firmware Configuration.h file to reverse the travel. I belive the value is ENDSTOPS_INVERTING = false on all 3 axes (XYZ).

Jan 22, 2015 - Modified Jan 22, 2015
heteroerectus - in reply to JorgeRdgz

I am used to standard cartesian style printers. If the end stops are at the top, how does the printer know where the bed is?
EDIT: Are there no end stops at the bottom? (ie. for x & y?)

I just finished with the build and everything went together pretty good, thanks for the design. I have just started the calibration and was wondering if you would post the settings you are using for the following.

Thanks again, turned out real nice.

Same here, I used your exact measurements, can you post these settings?

falcon20cne, how did you get it put together? I haven't found any instructions, and the pictures have no scale as to what go where. Or how far apart they need to be. I have everything printed, but no idea about where to cut the 80/20 to put the belt in, etc.

Anyone out there put together a assembly instructions set to go with the BOM?

Wow, you design looks really nice. I have a question for you though. I see in your carriage, you have slotted the holes for the bolts that hold the 608 bearings. It looks like you slotted booths sides

Sorry for the late reply, but my trusted 5y/o MacBook died on me during the holidays. Anyhow, I haven't noticed any shifting of the carriage. The rubber bands do a good job of applying the right amount of pressure. I can adjust the pressure by twisting another loop on the band. The platform with the Bowden hot end is very light so not a lot of inertial force. However, I can see how a heavier extruder setup might cause some shifting. Definitively something to keep in mind. Thanks.

Hi all.  Here is a list of new updates:
   1) I changed the carriage to use two 608ZZ per axle instead of one.  The 608s now ride on the flat at each side of the channel instead of the channel edges.  This required an extra 1mm on each side of the carriage.
   2) The axle is was modified for the new configuration.
   3) Added a spacer to the idlerClips to keep a consistent 6mm gap between each idler clip.
   4) I uploaded the new STL files and made changes to the BOM.

I haven't fully tested these mods but I assume it should all work the same since the major change just modifies the tracking of the carriage wheels to avoid getting stuck on the channel.


Did you ever resolve the skipping issue with the extruder stepper?

I am still having print quality issues.  I did discover a carriage design issue.  It didn't take that long for the ball bearings to wear away the thin edge of aluminum channel.  The bearings got stuck on the channel.  I modified the carriage to use 8 bearings instead of 4;  two in each side of the channel.  So the bearings will ride on the flat sided instead of the thin edges of the channel.  I am currently printing the new carriage and should be able to test in a few days.  I will upload the mods as soon as I get it tested.  Another problem for me has been setting the right amount of retraction.  The Bowden tube creates a delayed reaction which makes the retraction difficult to set.  I get lots of hanging material when at travel points and inside of holes.  I'll keep you all posted. 

hi, what's actula status, is is more reliable in actual version? I'm considering which to build, original rostock, or this one :) and this one looks much better, even though seems to be a bit more expensive ... :)

Do you have a ballpark estimate what the total cost of the BOM is?

Around US $600.

Hi, I am starting a build of your design.

I have some questions:

1 - In the BOM, it says that are needed nine 80/20 10 SERIES 1010 1" X 1" T-SLOTTED EXTRUSION x 274.32mm (10.8").  I wonder, if three of these are up, and three are in the base, where are needed the other three?

2 - I will be using metrical aluminium profiles, as I do not have access to the non metrical, inches style profiles. I have think in three T slotted profiles of 30mmx30mm and 800mm of height, and nine 30mmx30mm and 300mm profiles. Is there any reason why I should not do this? (I already know that I will have to modify the design of several of your pieces).

3 - Could you take more photographs of the whole running that do the belts around the aluminium profiles?

1 - 3 at the Top, 3 at the Base, 3 at the Heat Bed platform (middle).  Electronics and motors are placed under heated bed.  Check the new pictures.

2 - All PRISMA parts are design to fit the 80/20 1010 profile.  You can probably use a different profile, but then you will definitively need to modify the parts.  The carriage is one thing to pay attention to.  In the PRISMA, as well as in the Rostock Max, the 608ZZ bearings ride right on the very edge of the extrusion channel; since bearing width is 7mm and channel width is 6.5mm approx.  A wider channel would require the bearings to ride inside the channel, consequently the channel can not be any deeper than the width of the ring (5mm) or the bearing will not be tall enough to clear the bushing/axel and will not make contact.  Also, the belts travel within the T profile channel.  

3 - I aded more photos.  The entire length of the belt travels inside the forward T channel.  To make this work I had to widen the channel (cut a notch), near the HB platform and at the top,  to allow a 608 bushing to push the one half of the belt into the channel.  The second half of the belt rides a few mm on top, flush with the edges of the channel.  The first belt notch cut starts at 185mm from the bottom and the second starts at 50mm from the top.  The length of the notch is approx. 45mm.  Check the pictures.

Good luck and enjoy the building.

Thank you so much for the BOM! Keep up the good work!

Looks good and sounds a lot quieter than mine with the linear bearings. Is the clicking in the beginning your extruder stepper skipping?

Thank you.  It is kind of quiet.  I did spray the joints with Teflon Lubricant.  I am having a skipping problems with the Airtripper also the PTFE tube pops out of the M4 nut. I am going to replace the M4 bolt that holds the tube with PTC fittings.  I will have to modify the Airtripper so that I can tap with the appropriate thread for the fitting.  Hoping I can get this resolved in the next few days so that I can get back to having fun calibrating the printer.

Great looking printer! Can you please post a BOM or atleast the lengths of extrusion needed...looking forward to building one! Thanks!

This looks fantastic! I'd love to see and hear more about the build and assembly. I look forward to updates with more details!

From the look of Johann's blog, he's also working on a similar design: http://deltabot.tumblr.com/http://deltabot.tumblr.com/ . This looks like the 3d printer design to beat for doing tall prints. I want to build something like this for doing large scale prints of my full body scans (For example, see this 16" tall print that was done in 3 sections http://www.thingiverse.com/derivative:43366)http://www.thingiverse.com/der....

a real improvement IMO. looking forward to seeing if there are any noticeable difference in models printed with these delta bots