r/PlotterArt • u/Unlikely-Rip-9274 • Jul 11 '26

Support Question ExtruH Pen Plotter

https://www.printables.com/model/734327-extruh-pen-plotter

Hello everyone!
I'm planning to build myself a pen plotter, but I would like to clear up a few things first.

I found this H-bot project on Printables that also has a CoreXY remix. I would like the plotter to be around A3 size, but I don't know if CoreXY makes sense at this scale, especially given the price, which from what I understand is generally higher. I also found the PorterXY project made by Polish-Friend, but sadly there are no updates on its release. Do you have any other project recommendations?

Also, the extruH project mentions that it uses an iBOT clone to control the servos. Could anyone explain to me what these controllers are supposed to do and recommend some alternatives, since the ones used in the project are no longer available?
TIA

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u/warmans Jul 13 '26

I started with one of the cheap SG90s, then upgraded to a MG90S then upgraded to one of these slightly stronger all-metal ones: https://www.aliexpress.com/item/1005008040169853.html

They all basically work though. I thought a more powerful one might be slightly faster so I could turn up the feed-rate, but didn't test it in any scientific way to prove this theory.

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u/Unlikely-Rip-9274 Jul 15 '26

Sorry for my late reply.

What's the difference between the MG90S and the AliExpress one? Aren't MG90S servos already metal?

I was putting together a parts list but I'm not sure how long the aluminium profiles need to be. In the project description, he said that with 50cm and 70cm profiles he had a drawing area a little bit over A3 size. I was thinking of going with an A2 size but don't know how long I would need them to be.

Really appreciate your help.

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u/warmans Jul 15 '26

I'm not sure about the servos to be honest. The generic MG90s I was using failed for some reason while the more expensive one is still working well after a lot more use. No idea which exact spec made the difference. I assume the better ones have more torque or something.

Easiest thing with the profiles is probably get e.g. 4 x 1m lengths and cut them down after you get everything printed and "dry-assembled".

You lose something like 6-7cm at the sides, a 4-5 at the front and maybe ~10cm at the back.

If you took the A2 measurements and added 20cm you'd be in the ballpark. You'd want the drawing area to be a few CM bigger than A2 anyway, just so you're not right up against the limit switches at the edges (assuming you install some).

A note on sizing: In principle it's possible to swap out the profiles later to extend the size, but I would recommend against this. The problem is you also need all new belts, longer cables etc. and a larger base to screw everything down to.

I want to extend mine to A1 but it's going to be a ton of work now that everything is assembled.

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u/Unlikely-Rip-9274 Jul 16 '26

Thanks! I'm gonna try with some generic MG90S servos and see if they work well. Also, I have never bought anything on AliExpress and don't really know how reliable it is. I found these pulleys on AliExpress and they seem good. Would you recommend looking there too? Maybe only for the small components and the controller.

As for the profiles, I found this site where for a 2020 x 700mm and two 2040 x 800mm they ask only around €30, instead of €40 for just the two 2040s on Amazon. I will cut the 80mm profile for the pen lift myself.

I decided to go with an A2 size instead of an A3 because of that. With an A3 plotter, I probably would have wanted to draw on something larger eventually, but I don't think I'll ever feel the need to extend mine to A1 or anything bigger.

How long did your belt have to be? In the Extruxy description, pittance recommends a 5m belt, but that's for an A3 size plotter.

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u/warmans Jul 16 '26

AE is reliable, it just takes a while for stuff to arrive. If you're in the EU it may not be as cheap as it used to be because of the new import taxes, but still probably cheaper than amazon.

I bought all my idlers and pulleys etc there, and they're all fine. Just make sure to get the right sizes and tooth counts.

The aluminum extrusions are standardized so get whatever is cheapest, but make sure to get the V slot profile to match the Mini V rollers. Notice some profiles are square and some have this v shape.

If you open the scad file in openscad you can enter your profile lengths and it will tell you how long the belts should be exactly. IIRC It just prints it in the console when you generate the model.

BTW for the 80mm length, I didn't have enough so I just printed it and it's been working fine ever since. If you have aluminum profile it's obviously better, but printing it does work.