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Ender 3 double bed width mod and firmware upgrades
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Published
Feb 24 2021 by FaTe
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Quick jump
A lot of my future designs I have in mind are often beyond 200mm wide and printing in parts degrades strength. Some of the future projects include car chassis, full size single quad frame prints etc but I don't want to bigger on Y or Z as I don't require it.

Increasing the bed width seemed like a good idea until I realised I couldn't just increase the bed size in Cura... OK so I need to change the firmware.. Oh Ender 3 has no boot loader lol. So the only way to increase the bed width in a custom manner is to install a boot loader, make some tweaks in the firmware to alter the bed size I want, flash that onto the control card and.. voila! 420mm (X) * 220mm (Y) * 250mm (Z) printing capacity :D

What's needed?

- 20x20 extruded aluminium profile - 500mm length. This will be the new Top cross bar.

- 20x20 "" - 510mm length. X axis bar that the print head etc sits on.

- 40x40 extruded aluminium profile - 420mm length. The new bottom bar.

- 2 meter GT2 timing belt for the new X axis length.

- Aluminium crimping loop sleeve clips to put on the end of the belt ends when cut to length.
/theme/ender3/1 prior starting
One last look at the stock Ender 3 setup .. bye bye 220*220*250 printing!
/theme/ender3/2 ender 3 wiring to control board
Best to take some pictures of where all the wires go while I could. But in case you need one here it is.
/theme/ender3/3 fully disassembled ender 3
So to rebuild first take everything apart!

Everything has tape and is labelled down to the bolts.
/theme/ender3/4 ordered wrong extruded aluminium doh
I made a mistake when ordering the 40x40 aluminium length by not paying attention to the extruded type. With extruded aluminium not being exactly super cheap I wanted to come up with a solution to my cock up.
/theme/ender3/5 metal epoxy fill
I used some green low tack masking tape and wrapped it around the bottom and sides. Followed by pouring metal epoxy mix into the taped area. Once it set I removed the tape and was left with a workable area.
/theme/ender3/6 template mark extruded aluminium bolt positions
The bolt holes line up with the centre support arms but it wasn't going to give enough bite for bolts hence the metal epoxy.
/theme/ender3/7 extruded aluminium bolt pilot holes
Thankfully I got the pilot holes spot on but I was still concerned about strength.
/theme/ender3/8 bottom support cross bar centre line marking
So now it was time to cut the slot which the Y axis rail / motor and heat bed all sit on. It's crucial this next step go right otherwise a tiny degree off here or there translates to a lot more degrees at the corners of a larger bed.
/theme/ender3/9 cross bar y axis rail cutout cutting disk
First tool of choice is the Dremel with a metal cutting disk to get through the bulk of it.
/theme/ender3/10 y axis rail notch cut out
Once the bulk of it was removed a quick pass with a sanding bit on the Dremel to clean up the cuts.
/theme/ender3/11 y axis rail fitment
Once the holes for the Y axis bar were drilled one last check to make sure everything aligns correctly!

The bar closer to the camera is the original bottom cross bar that held the Y rail, can see it is somewhat smaller!
/theme/ender3/12 bottom rail wiring notches
The largest cuts in the whole process is the large notch out for the wires that lead out from control board unit. I decided I didn't want to trust the metal epoxy to hold the frame rigid, so I added a 2nd large notch on the right side so I could use longer bolts and put actual nuts on the end, strength issue solved!
/theme/ender3/13 bottom rail uprights fitted
It's time to begin putting everything back together. We start with the side posts going back in place. The control board / housing can also be fitted.
/theme/ender3/14 bottom rail additional support bolt fittings
As you can see now the longer bolts can be nipped up tight without worrying about stripping the threading in the extruded aluminium. While I did tap all the drilled holes it means I'm not constantly worrying if that metal epoxy is going to give. It's just all adding to strength and means if I have to disassemble for any reason I know it will go back together just as rigid every single time. If I had a work shop or similar I may have chosen a different path but I don't and this works.
/theme/ender3/15 ender 3 new 450mm top rail fitted
The 20x20 500mm length piece can now be fitted on the top. This time round its a simple case of drilling 4 x 5mm holes and half depth at 10mm diameter so the bolt heads can pass through and sit flush with the rail top.

Any eagle eyed people may notice the original top cross bar behind the printer on my mini work bench. It looks tiny now ha!
/theme/ender3/16 y axis final fitment
Finally the Y axis rail goes back in place with the head bed mount.
/theme/ender3/17 460mm x axis rail hole placement
Next up is the X rail bar which needs the holes for the wheeled mounts that run up and down the side posts.
/theme/ender3/18 new 460mm x rail fitted
Woohoo we finally have all bars back in place.
/theme/ender3/19 new 420mm 220mm 3mm 6061 aluminium hot bed
3mm thick 6061 grade aluminium sheet just instead of 220x220mm this one is 420 x 220mm :D

Now for the most important drilling of it all! The four pass through holes that holds the aluminium plate to the original heat bed, it has to be perfectly centred.

This was followed up with rounding the corners as they were pretty sharp.
/theme/ender3/20 new heat bed polished
Last step of preparing the new bed was to polish it until it was a mirror finish. Now it's ready to install.
/theme/ender3/21 ender 3 420mm 220mm head bed fitted
With the new top bed in place the print head can go back on the X rail. Now I have to fit the new belt to fit the X stepper motor. This is where the Aluminium crimping loop sleeve clips come in, once the belt has been measured and cut to length with some excess on each side (about 20-30mm) the clips can be crimped on. These then slide into the slots on the bottom of the extruder assembly the same way the stock version is setup.
/theme/ender3/22 new x drive belt fitted wiring fitted
Time to wire everything back up!
/theme/ender3/23 wiring pinned in bottom cross member
My only concern was wiring moving around in the cuts, although I rounded them I'm paranoid so I zip tied them all up.
/theme/ender3/24 ender 3 extruder motor wire not long enough
Unexpected problem #1

The extruder motor lead was no longer long enough to reach all positions so an extension is required.
/theme/ender3/25 ender 3 extender stepper motor lead
I found a longer cable and soldered on the extension.
/theme/ender3/26 new ender 3 control panel left side mount
So problem #2

The control panel will no longer reach to the right side, not by a long shot!

I didn't fancy changing more cables so I rattled up a mount which bolts onto the left side and mounts the control panel plate. Was also the first print!
/theme/ender3/27 new ender 3 control panel fitted
Now the control panel can mount on the left and still be out of the way of the print bed.
/theme/ender3/28 usb programmer update ender 3 firmware boot loader
Problem #3

Thinking I could just update the bed size in Cura and be done was a nice idea but alas no ha.

I found out I would have to update the firmware ok not so bad, until I read on and found out the Ender 3 doesn't have a boot loader. A boot loader is required to get the control board to connect and accept updates to its firmware. So I purchased a KeeYees 2pcs Downloader Programmer for USBASP for ISP with Cable and 10Pin to 6Pin Adapter Board for 51 for AVR Series Microcontroller

You can then connect the control board using the socket the screen normally plugs into to the USB controller and then to your PC. Once the boot loader was installed (there are various guides for this in google) the control board would then begin accepting firmware updates. You only need to install the boot loader once after that you can use the USB connection on the board from then on!
/theme/ender3/32 usb boot loader update arduino
If you want a complete firmware package then I recommend TH3DUF_R2 (at this time early 2021). It took some digging but I found where to edit the bed size so the printer will then actually print to the new larger bed size!
/theme/ender3/33 cura new bed setup
Now back to my slicer to update the bed size settings and voila now I can print to the whole bed size :D
/theme/ender3/31 first test print 3dbenchy
So whats the first print off the bed???

A 3DBenchy obviously! (find it here on Thingiverse)

Except for needing the slightest tweak on the final retraction at the end of the print I'm super happy with the results. I can still fine tune and tweak further but I'm pleased the printer is back operational.
/theme/ender3/34 upgraded ender 3 build finished
As for cable management I could of went with printed tracks and all that jazz but in the past I found them to be not exactly quiet. I prefer to route the main loom cable for the extruder motor / fans / hot end through a 2mm piece of piano wire I bent into a loop shape and bolted into the side of the frame. This suspends the wire but moves freely with the printer.

To stop the cable from there to the rail drooping on the bed I used a platform I quickly printed which sits between the spool and top rail pinned in place by the spool itself. I used an elastic band loop to act as the carrier but since replaced it with a small piece of bungie cord.
That is the whole upgrade process done. I'm mega pleased I can print up to 40cm wide as that opens the door to a lot of RC projects printed as single solid pieces. Learning about the firmware process and understanding how to tweak what I want in firmware was a nice learning curve and not so hard. You can do all sorts like custom flash screens, extra menu options on the control panel and more.

One of the best reasons to update your firmware even if you are not rebuilding the printer is the thermal runaway protection in the updates which doesn't exist in the stock Ender 3. This stops the print head from ever getting too hot outside its operating range and starting fires ... (it's happened). So given the price of the USB connector and all the rest being free downloads it's really worth doing.
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