Original Prusa i3 Mk 2 kit

[Delta Foxtrot]

Trevor,

It is an interesting challenge to work with new materials. I expect that a lot a parts will be relatively lightly loaded compared to the material strength in any direction, in which case the print orientation can be chosen to minimise supports etc. With higher stressed parts more thought is needed towards maximising strength.

I may make a bit of a start on the build tomorrow.

Cheers
Dave

[Ian Jones]

Posted by Delta Foxtrot on 24/02/2017 20:19:15:
Trevor,

It is an interesting challenge to work with new materials. I expect that a lot a parts will be relatively lightly loaded compared to the material strength in any direction, in which case the print orientation can be chosen to minimise supports etc. With higher stressed parts more thought is needed towards maximising strength.

I may make a bit of a start on the build tomorrow.

Cheers
Dave

Yep, and if there is a choice then treat it like you would wood grain.

Joining the growing ranks of budding 3D builders DF, I reckon it's going to be big .

Edited By Ian Jones on 25/02/2017 00:32:59

[Trevor Rushton]

Thanks both and Dave, good luck with your build. I don't think that you will find many complications (the instructions suggest moderate difficulty) although I have "enjoyed "a few small frustrations -one being the fitting of the psu which, with only 4 fixings ought to have been easy. It wasn't! The nut retainers that are moulded into the printed bracket on the main y axis frame seem to be the wrong size for the supplied 3mm nuts. However, the bolts do cut their own thread into the part, but I could not get the nuts to bite, they kept falling off. I will have another go today.

I need to make some small adjustments to the x axis to align it normal to y; the method described in the instructions is a bit hit and miss- I will use a square rather than a visual alignment, but adjustment of the 10mm nuts looks to be simple enough - I would have thought that the correct positioning of the frame could have been made easier by using sleeves of the correct length on the studs - but its not a big deal.

Cable management is interesting - I have not installed the electronics yet but there are lots of wires! I am still finding the extensive use of cable ties a bit odd - fine for fixing cables but they are also used for retaining things like the led screen assembly - no reason not to I suppose but it lends a bit of a "jury rig" feel to the whole thing - this should not be a surprise given the evolution of this type of machine.

Total build time so far - 5 evenings at circa a couple of hours each - I probably need one more session to install the electronics, adjust and calibrate before the real fun starts. Sadly the Boss is becoming critical over the delayed completion of house decorating so I may have to divert time to that instead. Ho hum.

[MaL]

I was just a little concerned with the longevity of an acrylic frame..

**LINK**

got mine from this guy

**LINK**

it has the capacity for a larger than normal print bed at 200x300mm, although at the moment I just have a 200x200 heatbed fitted

For cable management I used this stuff

https://hobbyking.com/en_us/wire-mesh-guard-neon-green-8mm-1m.html

Edited By MaL on 25/02/2017 17:34:27

[Delta Foxtrot]

Trevor,

I built the y-axis today, a bit fiddly in places but not too bad on the whole.

The y-axis is not exactly silky smooth when pushed by hand, in fact it is a little stick-slip. I played around with the belt tension, which is a bit hit and miss, backing off a little did not make the action much smoother. I am not sure if this will be an isssue or not when driven by the stepper motors.

I would ve interested to know how yours compares.

Dave

Edited By Delta Foxtrot on 25/02/2017 18:36:16

[Delta Foxtrot]

Problem solved! I read through the comments on the Prusa build webpages and I just needed a small clearance adjustment to the motor pulley.Lesson learned!

[Delta Foxtrot]

Mal,

Do you have the i3 mark 2 or an earlier i3?

[MaL]

I bought the Prusa P3Steel v4 as per the link I gave.. The STL files are freely available on the RepRapWiki site I linked if you have access to a suitable laser or waterjet cutter, or, if not, it is still available on ebay from a slovakian seller that I also linked in my earlier post.

It is essentially the same as the i3 that you find available in either acrylic or plywood, there are some differences between all the iterations but nothing dramatic, (The V4 has the larger print bed though..) for example, the trend is now to use 10mm smooth rods for the Y axis and 10mm threaded rods or leadscrews for the z axis, some of the acrylic and plywood versions are still using 8mm Y rods and 5mm Z.. My P3steel has 10mm smooth rods for the Y and 5mm threaded for the Z. Its just the sort of thing you decide to change after living with your printer for a while and decide to improve it.....

The advantage of buying just the frame is you can fit whatever other bits you like . better electronics, different stepper drivers, different sensors and so on....

 

Since I bought mine I see there is now another development.. a PROBOT.... nothing stands still for long!!

Edited By MaL on 25/02/2017 20:08:58

[Delta Foxtrot]

Thanks for info Mal. I am new to all of this technology so not too familiar with the different versions of the Prusa printers. The major components for i3 mk 2 framework are steel bolts and aluminium frames, not acrylic.

I will take a look at the links you posted.

Cheers
Dave

Edited By Delta Foxtrot on 25/02/2017 20:15:43

[MaL]

The Prusa i3 mk2 does look nice and it is receiving good reviews...but at a price (list is 739euro)  The controller, for example, is a mini rambo that is generally considered to be an improvement over the arduino2560/RAMPS controller but in my view it is not worth the premium..£140 versus £25 ..it's not even a 32 bit processor....

3mm aluminium frames are good but I'm not sure how flat the PCB will be after cranking the temperature up a few times to print ABS or some of the more exotic plastics..only time and experience will tell.

I would recommend anyone thinking they want to buy into this hobby think very seriously before shelling out this kind of cash, my advice would be buy a cheap clone and get to understand how to fix problems and then if you think you have the requirement go and buy/build an accurate printer..

Edited By MaL on 25/02/2017 20:35:52

[Tony Bennett]

The Anet A8 is a good cheap printer to start with.

£140.00

mind you it is all self assembly, so you learn a lot building and setting it up for printing.

It does print well though once you have it working ok.

Tony B

[MaL]

Thats very nice Tony..what sort of size is that? and how was it orientated on the build plate? (I take it the glove boxes are glued on)

The advantage of buying a kit over buying just a frame is that all the calibration will have been done for you so it should produce results straight 'out of the box'. The other side of the coin is that once you have the correct steps per mm, zerk, max acceleration, temperature calibration et al. it doesn't change and it is helpful playing with these figures while setting a printer up to understand how to fix printing artifacts if and when they occur.

[Tony Bennett]

the cubby boxes were made separately and glued on later.

i set it flat on its back but diagonally along the bed as it was 220mm long.

Tony B

[Delta Foxtrot]

Nice print Tony, looks like you are cracking on nicely.

[Delta Foxtrot]

X-axis assembled. Enough for today, I am tackling this in small chunks to avoid distressing my back.

So far I am very impressed by the quality of the on-line build instructions and the access to comments from builders and JP.

The bearings work but they are not silky smooth, I expect that they will improve with a little running in.

[Delta Foxtrot]

Trevor,

Did you need to retap any holes during the z-axis assembly? I have seen comments suggesting problem getting m3 screws to screw into the frame.

Cheers
Dave

[Delta Foxtrot]

I just checked the threads and they are fine. It is impressive how Prusa listens to the feedback and fixes problems as they are reported. I have had none of the part fit issues reported by earlier builders.

Edited By Delta Foxtrot on 26/02/2017 14:13:22

Edited By Delta Foxtrot on 26/02/2017 14:13:50

[Delta Foxtrot]

Mal,

The i3 mk2 frame is 6.5 mm aluminium, not 3 mm.

Cheers
Dave

Edited By Delta Foxtrot on 26/02/2017 15:12:49

[Trevor Rushton]

Dave

I did not have to tap any holes other than by screwing in the various machine screws. The hardest ones were those that fix the Rambo box to the frame; its worth screwing those in first to cut a thread but no real problems. I think that the final stage took a bit longer than I anticipated - I'd say I spent 6 evenings at a couple of hours each evening to complete it plus a couple of hours messing about with final adjustments and calibration.

I agree with you, the bearings do tend to stick a little, but they don't seem to be causing any problems in use.

Mine is now up and running; calibration was fairly easy but I did make a couple of errors. My self test failed as I ad not connected one of the fans correctly - getting all of tthe iwires in is a bit fiddly and if, like me your eyseight is not good for close up work, the combination of a black background and artificial light was a pain.

I found some difficulty getting the print to stick to the bed; the supplied Pritt stick improved matters but in the end I used the live z adjustment to set it at -.35 - that seemed to do the trick. The machine is now busy printing a tree frog as a test piece - don't ask me why a tree frog other than this is on the sd card and is seemingly commononly used for comparison purposes; Its been chugging away for about an hour so far. If that turns out okay I shall prepare a 20mm cube to measure the accuracy.

Good luck with your build - I am not sure that I enjoyed every minute of mine but I think it was worthwhile because I now have a good idea of how these things work and tthe function of the various components. Short bursts and patience are the key I think.

T

[Delta Foxtrot]

Trevor,

Thanks for the information.

Good to hear that you are up and running. I do not think you should need pritt stick for PLA, I think the Z adjustment was the way to go.

I am quite enjoying the build so far. I have now completed the X,Y and Z axis assembly. Sounds like there could be some fiddly bits to come.

Cheers
David

[Trevor Rushton]

Thanks David

The frog is complete and I am delighted with it. The Boss was impressed and is already thinking up projects to print. Resolution was superb; I am really chuffed.

I abandoned the test cube and went straight in and designed a pen holder for my Stepcraft - I have just rebuilt that following problems with the Y axis; using a pen is a cheap way of testing it without cutting out and wasting material. Started to print it but at high resolution it will take 4 hours. I need to experiment with lower settings but the measurements of the 30% that I printed are spot on. (Slight disagreement about leaving it running overnight! I backed down.)

T

[Delta Foxtrot]

Trevor,

I am pleased to hear that you are happy with the printing quality and have the Boss on-side. No stopping you now, except at night time of course.

I have been wondering about potential running restrictions due to noise, and the length of time taken to print parts. I wonder if it is safe to leave the printer running unattended during long print runs, I would generally keep a close eye on heated machinery just in case, but with prints taken several hours that could be a bit of a bind.

David

[Trevor Rushton]

David, I did not find it very loud so I guess you could shut it away somewhere overnight. As to whether its a good idea I cannot say; common sense suggests probably not.

Long print runs could be a bind - the maximum evening run for me would be about 3 hrs - 4 at a stretch. I might be overdoing it in terms of resolution, but when I bought the Prusa I was looking for something that would give a high quality finish so I guess I will have to print at weekends - or make smaller parts!

[MaL]

It is quite surprising how far the low frequency noises carry in the dead of night! sometimes the rhythmical tunes coming off the steppers aid the quest for sleep......sometimes not, I find myself listening for the z carriage lifting at the end of the job

I think the accumulated wisdom is that you buy a smoke alarm and place it over the printer if you are going to leave it running unattended.

[Delta Foxtrot]

Yes I think the smoke alarm is a no brainer, but it still means you have to be on hand for potentially very long periods when printing large parts. I guess that is the nature of this beast.