tekkydave

I have yet to implement auto levelling on this printer. I haven't decided on proximity or servo/microswitch. Any thoughts?

Yep. 300x300x6mm ecocast Ali adds a bit of weight. It's not too bad if you get it balanced but a bit fiddly. To be fair I used to get backdriving on my Prusa using the 4-start screws. They are not really suitable - 2 start would be a good compromise between speed and accuracy I think.

Yes, I was considering doing that myself. The D-Bot is designed for light PCB style heated beds not the 6mm Ali like I'm using. The cantilever is not really up to holding the weight without a bit of droop. Some use 3 lead screws which is what I'll try first as it is easy to implement but I may end up going the way you have. I may do it as a general upgrade to 3-wheeled carriages all round.

I took a trip to B&Q the other day and picked up some 1mm thick discs for my angle grinder. Today I shortened the new lead screws to 410mm. I ground an approximate 45deg finish on the cut ends to avoid any nasty burrs. I didn't bother trying to clear the threads as the cut ends will be in the flexible couplings. I fitted them to the D-Bot and they work very well. The bed doesn't back-drive the motors now and move down under it's own weight I temporarily changed the Z steps_per_mm to 3200 using M92 for testing: M92 Z3200 I need to make this permanent in the firmware and also adjust some of the speeds as the movement is far too fast for these screws, especially the Z homing speed which tends to stall the motors. I have a 3rd screw and a spare motor so I'll be trying to add it in at some point to give better support to the heavy bed.

Good progress, Gina. I love your "make it up as you go along" methodology. I don't have the confidence to do that myself. I tend to take working designs like the Prusa and D-Bot and make improvements where possible. Best luck with your build

Ooo, another printer topic. I'll pop across and read up so far

I've also been busy designing and printing an enclosure for the IEC C14 inlet and Solid State Relay. The plan is to keep all the mains voltage wiring together and separate from the rest. A mains feed from the box will feed the power supply. The SSR will have 12V input from the RAMPS and mains output to the silicone heat pad.

The new leadscrews arrived this p.m. They look pretty good quality with nicely finished ends. These are 8mm dia, pitch 1mm, lead 1mm, single start. For some reason I ordered 500mm length, but I need 400mm for the D-Bot. I'm not sure how easy they will be to cut. I'll have a go with a hacksaw or maybe my angle grinder. The narrowest metal-cutting disc I have is 2.8mm. Maybe a 1mm would be better.

I've ordered some single-start T8 lead screws. These will have a pitch and lead of 1mm as opposed to the 8mm lead my current ones have. This should stop the sagging (hopefully). I've ordered 3 so I can upgrade to a triple drive system at some point.

Yes, I thought ABL would not be relevant. Maybe some kind of braking mechanism is needed or keep the z motors energised. In a normal printing situation its not an issue as they are permanently energised during the print.

I have temporarily connected up the heat pad via the SSR to test it. The bed now heats from room temp (21C) to 65C in about 30 seconds. Should be fast enough . No picture as I dont want to encourage exposed mains voltages I did add a grounding point to the metal part of the bed for safety. The glass arrived today so I installed that and did a PID tune for the full shebang. I discovered that the thermistor types used in a lot of these beds needs to be set up as type 75 in Marlin #define TEMP_SENSOR_BED 75 One thing that is now happening is due to the weight of the bed it now sinks down the leadscrews under its own weight when the motor power is off! Maybe some anti-backlash nuts might help, I'm not sure.

I've also ordered a piece of 300x300mm borosilicate glass from Ooznest to give a nice build surface.

I have drilled the mounting holes in the bed plate and countersunk them so a glass plate will go over the top. Today I attached the heat pad to the plate and fitted it to the printer. I cut some PTFE spacers from some bowden tube to keep the metal mounting screws and springs away from the cut corners of the heat pad. I'm sure the heater wires are still about 5mm from the cut edge but you can't take any chances with mains voltages. I needed to adjust the positions of the z motors, bed mountings and z carriage 'arms' to accomodate the larger bed. I also moved the z motors forward as the centre of gravity of the combined bed assembly had moved forward significantly. I should have removed the entire assembly from the printer and found the balance point manually but I think I have it in approximately the right place. I intend to upgrade to three lead screws with a single motor at some stage so it will all get rearranged at that point anyway. I have connected the bed thermistor up to the RAMPS and updated the necessary Marlin configuration, moved the endstops etc. Next step is to wire up the heat pad to 220V via the SSR. I will also be ensuring the metal parts are all grounded and the bed supply is also fused.

It should work but you will need to rewrite the clockwise() and anticlockwise() functions to suit the stepper controller. Good luck.

Thanks for that To be honest I haven't even touched my scope for a couple of years now <shame>. I seem to have been completely taken over by the 3D printer bug.

A couple of pics: I would strongly advise anyone doing something similar to get a slightly oversized plate, e.g. 310x310mm or 320x320mm to make life easier.

The Silicone Heater I ordered has arrived. I made the mistake of buying a metal base 300x300x6mm so leaving no room for the mounting screws. I have managed to snip approx 6mm diagonally from each corner of the heater to clear some space. I could just see where the wires were inside the heater and I had my DVM connected measuring resistance but it was heart-in-mouth time whilst cutting Next job is to drill and countersink 3mm holes at each corner for the mounting screws.

Well thank you for saying so

Your description just reminded me of the Tom Hanks film 'BIG' Maybe you should call it 'Hanks' or 'Tom'

Designed and printed a couple of brackets to mount my ATX power supply on the V-slot frame. I will need to add another cross piece at the bottom level to bridge across to. I now need to design an enclosure for the electronics in a similar fashion to hold the Ramps, RPi3 plus any other electronics I need to incorporate. I've also bought a piece of ecocast aluminium plate 300x300x6mm to give me a larger print area. I've also ordered a 300x300mm silicone heater (750W @ 220V) and a solid-state relay to interface it to the Ramps o/p. Both on the slow-boat from China so will take a few weeks to arrive.

I think I've cured the issue with the Titan and 3mm filament. I replaced the stock tensioner spring with a similar one which I shortened to about 2/3 of its length. I now have a better range of adjustment and can slacken it off far enough so there isn't excessive pressure on 3mm filament. The white filament is now extruding happily at 220.

The Titan has been performing pretty well so far except when I use filament that is a true 3mm diameter. The 2.85mm filaments seem to be ok but 3mm causes the drive to skip steps. I have the tension spring all the way out. I suspect the pancake stepper motor doesn't have enough torque (21Ncm) to push the filament through the hot end. The latest batch of white filament I have bought from WeDo3DPrinting needs to be extruded at 240°C to be fluid enough to go through without skipping. I've checked the stepper driver volts and it is 0.55 which should be correct. I might try fitting the motor I was using on the Prusa extruder. It's heavier but should give me some more torque (36Ncm).

It is partially accessible but I tend to use the manual extrude button on Octoprint to push the filament through. There's not much scope to turn the extruder to face front due to the geometry of the printer. I am losing about 20mm in Y as it is by using the Titan over the stock DBot extruder which is a bowden. Another printer! I wish I had the space

Finally got round to printing an updated Titan bracket for the DBot. This pushes the extruder out by another 5mm so the front panel screws become accessible without removing the belt clamp. I also fitted the belt clamps I printed in PLA rather than PETG. The 'grippy' parts printed better on the DBot and grip the belt without relying on just the tie-wraps. I also fitted the low-profile M5 bolts all round. With everything installed and working I printed up some adapters to re-use the vibration dampers from my old Prusa on the DBot. Remember these? They cut down the vibration & noise through the desktop by a huge amount.

I have matched as many settings as possible but I always feel Cura is doing its own thing behind the scenes. It produces better support structures than Slic3r though