thereprapkitstore.com Prusa Mendel construction Notes/Discussions

OK, got my Batch 2 (27/4) RepeRap last Tuesday and have started construction. I thought it might be a good idea to start this thereprapkitstore.com specific thread as I have already noticed differences between this kit and the kit described by the assemble instructions at RepRap WiKi.
The first thing to note is that this kit was shipped with parts missing, namely the electronics, bed heater and glass, both drive belts and hobbled bolt (what ever that is). but most of the construction can start whilst waiting for these parts.

thereprapkitstore.com refers to the fact that instructions will be posted on the wiki. The only instructions that I have found refer to the standard Mendel Prusa.

The parts are packaged and labels beautifully and are of high quality. I was very impressed with the quality of the ABS printed parts and, if these parts were made by a thereprapkitstore.com Mendel Prusa then we are in for a treat!

I'd like to make a suggestion to those posting to this thread: - Try to make your posts relate to only one thing, i.e one question or one piece of information. This will make it easier to link answers and discussions to particular posts. But, hey, it's an open forum, so do as you wish

Edited 1 time(s). Last edit at 05/11/2012 02:40AM by MotoBarsteward.

Difference: this reprap uses linear bearing bushes rather than printed ones. The standard instructions do not describe how these should be installed however, I think its pretty obvious. I made sure the the ends of the smooth bars were rounded off to protect the rubber end seals on the bearings.

Edited 1 time(s). Last edit at 05/11/2012 02:55AM by MotoBarsteward.

Question: What lubrication should we be using with the linear bearings?

Difference: The threaded rods supplied make the reprap 34 mm wider than the standard Mendel Prusa. Haven't found why or if it makes any difference yet.

Difference: The smooth rods that carry the bed sit above the threaded rods rather than hanging below as in the standard Prusa.

Edited 1 time(s). Last edit at 05/11/2012 02:55AM by MotoBarsteward.

Difference: the whole construction of the bed is different to the standard Prusa in that the bed is made from aluminium. This means that you can use the standard Prusa method for aligning the parallel smooth rails. I use a Vernier calliper instead. This design has two bearings on one rail and one on the other. I'm not sure if it matters which side has two and which has one so I've put two on the left rail (Y axis motor to the rear) and one on the right.

Warning: I found, on several of my threaded bars, that the thread on the end was damaged by the cutting process. This makes getting the nuts on that end difficult or impossible. Even running a nut right down from the other end didn't resolve the problem. Fortunately, I have an M8 1.25 die which ran down the thread from the good end and off of the bad end using a cordless drill on slow.

The instructions are here: [reprap.org]

I file or grind threaded rods to chamfer the ends. That then allows a nut to reform the thread as long as you can get it on one end. I llso make sure there is no burr on the smooth rods as that can knock out the balls from the linear bearings.

The bearings are pre-lubricated but I find they X ones can dry out due to the heat of the bed. I put a drop of light machine oil on the bars if that happens.

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[www.hydraraptor.blogspot.com]

Question: I am attempting to assemble the Z axis threaded bar assembly and I think I've run out of parts and instructions!

Firstly, the two part printed coupling that attaches the treaded bars to the stepper motors is too big to clamp onto the stepper motor axle. In my kit of parts, I had a 30mm length of clear plastic tubing. Is the idea that this pushes onto the axle and is clamped in the coupling to provide stress releaf to the motor? If so, then should there, in fact, be two pieces of this tubing? If I'm barking up the wrong tree, can someone point me to the right one please?

Secondly, the standard Prusa instrucion on the WiKi show two nuts and a spring in each of the Z axis printed part hexagonal buckets. This arrangement looks like it's intended to removs end play from the 'worm drive' that moves in the Z axis. My kit is missing these springs. Is this an oversight on the part of thereprapkitstore.com or are they deemed unnesecessary?

These questions are only being asked becasue the ABSPrusa assembly instructions appear to peter out in the last page and, I don't think, describe the final stages of the assembly in enough detail.

Edited 1 time(s). Last edit at 05/11/2012 04:28PM by MotoBarsteward.

Yes, the tubing is supposed to go over the stepper shafts. 30mm is a little short for both motors. Maybe cut it in half and slide it on. What's the worst that will happen? You'll need to get some more tubing. It's fairly cheap, and if you're lucky is sold to length. Don't be afraid to make mistakes - at least inexpensive ones! : )

The springs for the z-axis aren't necessary, but are recommended. Google 'backlash (engineering)' and it will become apparent why you want those springs. If they aren't on the BOM then I'd pop out to the hardware and get some before you assemble much more on the Z-axes. Just make sure that the spring isn't too long or short or stiff!

Keep at it - it'll come together!

---

- akhlut

Just remember - Iterate, Iterate, Iterate!

[myhomelessmind.blogspot.com]

I was thinking that you'd be able to see a length of clear tube between the end of the axle and the start of the coupling but now, having had a really good look at the photos of the ABSPrusa, I can see that it only needs 10mm on each axle just to increase the diameter of the axle for the coupling. I'll have another go tomorrow.

I've got some springs in there now but I thing they're a bit feeble. Thanks for your help.

I'm going to have a go at making the hobbed bolt tomorrow when I can get an M8 x 60 that is smooth for enough of its length. The one I tried tonight is threaded all the way up and I can't make the waste at the file catches the thread and is thrown to once side all the time. I think I know someone who has a lathe that I can use.

So, All I need is for James to come up with the belt, electronics and hot bed and I could be printing next weekend.

akhlut Wrote:
-------------------------------------------------------
> Yes, the tubing is supposed to go over the stepper
> shafts. 30mm is a little short for both motors.
> Maybe cut it in half and slide it on. What's the
> worst that will happen? You'll need to get some
> more tubing. It's fairly cheap, and if you're
> lucky is sold to length. Don't be afraid to make
> mistakes - at least inexpensive ones! : )
>
> The springs for the z-axis aren't necessary, but
> are recommended. Google 'backlash (engineering)'
> and it will become apparent why you want those
> springs. If they aren't on the BOM then I'd pop
> out to the hardware and get some before you
> assemble much more on the Z-axes. Just make sure
> that the spring isn't too long or short or stiff!
>
> Keep at it - it'll come together!

There we go, about 8 hours and help from this forum...

Looks good! You're about half way there - the rest of the hardware is fairly easy. It's the electronics that can be a pain and may eat a significant chunk of time.

How'd you make out with the hobbed bolt?

---

- akhlut

Just remember - Iterate, Iterate, Iterate!

[myhomelessmind.blogspot.com]

akhlut Wrote:
-------------------------------------------------------
> Looks good! You're about half way there - the
> rest of the hardware is fairly easy. It's the
> electronics that can be a pain and may eat a
> significant chunk of time.
>
> How'd you make out with the hobbed bolt?

The hobbed bolt was not sent with the kit. I decided to have a go at making one myself with the thought that if it turned out rubbish then I'd be getting one from James soon when he shipped me the rest of the kit. I went to B&Q and bought a few M8 x 70 bolts but they was threaded all the way up. I had a go at fileing a slot in it using the 'cordless drill as a lathe' technique but the file kept catching the thread and whistelling away from where I wanted the groove. Not to be beaten, I went to ScrewFix where they sold the ideal bolt! Only I had to by 100 of them! £10 later at least I knew that I'd could have a fair few goes at getting it right but, sods law prevailing, having a hundred spares meant I got it right first time! I put the bolt through the bearing using a couple of nuts and washers the secure one of the bearings to the bolt. I used a couple of G clamps to hold the bolt down onto the desk by the bearings so the bolt was free to spin and applied an M3 tap at 90 degs to the bolt into the slot. It knurled up well and appears to hold the filement very securely when threaded into the extruder. The bolt is making clear and regular marks on the filiment so I think it's going to be OK.

PS I have 99 other bolts. Got any ideas what I can do with them?

Hold onto them for your next extruder or machine. You will wind up with both eventually.

---

- akhlut

Just remember - Iterate, Iterate, Iterate!

[myhomelessmind.blogspot.com]

I suppose I could go into business making hobbed bolts! I'd better not give up the day job though.

Edited 1 time(s). Last edit at 05/14/2012 03:16PM by MotoBarsteward.

Hi,

just for your info... i followed this instructions which matches mostly, i also added some comments in there where things are different from the instructions. (search for pet110 to find the comments)

[reprap.org]


there is a fantastic guide for the wades extruder here:

[github.com]

Best luck with building, my missing parts arrived today

Peter

I think you have edited the wrong page. This is the one for the new kits: [reprap.org]

---

[www.hydraraptor.blogspot.com]

This would have been an easy mistake for pet110. I made the same mistake but decided to refrain from editing the wiki because the diferences were big enough to warrant writing a whole new set of instructions. I didn't realise that the ABSPrusa page existed in the wiki because I didn't realise that the RepRap kit store one was an ABSPrusa so didn't realise that that was what I had to search for. In fact, there are no links into the ABSPrusa page and you can only find it by searching. I'll have a look this evening at editing the wiki to make finding these new kit instruction easier without having to search.

nophead Wrote:
-------------------------------------------------------
> I think you have edited the wrong page. This is
> the one for the new kits:
> [reprap.org]

That is what it is called on the products page: [www.thereprapkitstore.co.uk] but I agree there should be a link to the instructions from there, and also included with the kit.

---

[www.hydraraptor.blogspot.com]

Hi,

mistake is recognized... i was quite annoyed that all kind of measurements where off, would have been so much easier with the ABSPrusa page.

will remove the edits tomorrow... need to build right now

I made the same mistake. However, I'm a firm believer in the rule 'If it gets difficult, you're probably doing it wrong' and my spider senses were definitely tingling which is why I opened this thread. nophead pointed out the errors of my ways and told me where to find the correct information.

In the AbsPrusa-Wiki, the two steppers are mounted with one nut distance to the upper vertex.

The product photos on the sellers page however show the right one with FOUR nuts in between.

I guess, that way, no x-axis space is lost because of the end-stop below.

I propably will go that way.
roland, ideas welcome.

Edited 1 time(s). Last edit at 05/24/2012 04:34PM by roland.

I went with a different approach on mine - since all of the horizontal threaded rod was cut longer than necessary, I made my frame an extra 15mm wide. Makes getting the full 200mm print width fairly easy.

I also only have one nut between the stepper and the frame which give me most of the X axis. However, with my Y stop switch where it is, mounted up against the smooth bar support on the oposite side to the Y stepper, I am loosing quite a bit of Y travel (45 mm). I think I might push the smoth bar through and move the y stop switch to the outside of the support.

OK, so what have I been up to since my parts arrived. Well, now I have a fully functioning ABS Prusa ><

I had some real fun trying to get the host software working under Ubntu 11.10 64 bit. Just about everything I tried failed! I tried Arduinio 1.0.1 but couldn't get SPrinter to build no matter what suggestions I found on the internet. The standard RepRap host software woulld not connect. In the end, theonly thin I could get to work was RepSnapper. Unable to calibrate the extruder, i tried printing the Wadebts.stl file ( the two extruder cogs and end bracket). The results were recogisable but that was about it. I later realised that part of my problem was that I was extruding PLA at 215 Deg C.

I also learnt that, when using Kapton tape on the bed, a little, insignificant bubble get really big when heated to 80 DegC and has molten PLA at 215 Deg C dropped on it!

In a fit of frustration at not being able to get the firmware to build, I spent the night installing XP on my machine. Installed Arduino 018 and the latest sprinter, I was able to calibrate my extruder. What a difference an OS and a bit of calibraton makes. The parts are a lot better. The only problem I have is that my J-Head 0.4 mm developd a habit of extruding PLA sideways. This ment that there was a tendency for PLA to stick to the side of the ozzle and drag off previously deposited beads. I decided to strip own and slan the nozzle looking for blockages. I used a PSU to heat the head up to aid deisassemble and re-assemble. This made no difference! But, the poblem appears to have sorted its self enough for good printing to return.
Picture



So, today, I printed something that I would thought would be useful for another toy that arrivedin the post yesterday. I downloaded and printed a case for my Raspberry Pi. It printed ver well. I was very impressed. Pity the design was about as much use as a chocolate tea pot! I don' think the guy who designed it had actually seen a Raspbery Pi. He' made no provision for the SD card and the 'reinforcing' around the RJ45 socket prevented the lid going on. I have noticed that the corners have curled away fro the bed a bit.
Picture

So, my piece de la resistance!

I couldn't end the weekend without printing Yoda! Even my wife was impressed! I modified the slicer for him to only use a 10% infill but he still took over 2 hours to print. I am, quite frankly, amazed by him.
Picture

In conclusion, I've not bought one of these machines until now because I was concerned that I would be eternally disapointed by the print quality.
I am honestly blown away by what this machine can do despite the fact that it was built by me in my garage!

So, only a couple of small problems to sort but I also have to find a way to de-real the filament without it getting tangled.

Edited 1 time(s). Last edit at 05/27/2012 05:12PM by MotoBarsteward.

Nearly finished with the mechanics, by now i am really happy with this ABSPrusa :-) Far better details than what is shown in the video tutorial of the original Mendel.

I have started to add some user-know-how to that little wiki page i started: [reprap.org]

roland
[www.scriptdoctors.org]

Edited 1 time(s). Last edit at 05/31/2012 06:44PM by roland.

Hey all, glad to see some others working on the same project as I am! I've also finished the frame and mechanics, just have to wait on a crimper before I can get started on the electronics.

MotoBarsteward, or anyone else who has recently built it - since the instructions for this kit end before the electronics, any advice for those of us about to dive in? Also, what pieces did you use to go about mounting the heated bed to the aluminum y plate? Is that what the hex posts are meant for, or did you use some of the longer bolts with a number of nuts in between?

In the photos a white board of some kind is shown for mounting the electronics. This was not in the kit. I had a bit of clear polycarbonate 3mm sheet lying around so I used that.
I soldered my crimp connectors on which took most of the time for wiring the electronics. It was very fiddley and not easy to get the terminals into the blocks but I managed it in the end.

There were four standoffs in my kit, ie hexagonal posts with an m3 screw on one end and an m3 hole at the other. The holes in the heater pcb are very tight and I had to loosen off the nuts on the standoffs and pull stuff around to get the holes on the heater to line up. I will be re- wiring my heated bed as the wire supplied for the job is not man enough and I'm loosing nearly 2 volts in the wires. Consequently drafts and cooling make it very difficult to keep the bed at 85 degrees. I used 2mm2 speaker wire (soft and flexible) for the print head. I shall do the same for the bed.

On the subject of the head. Various instructions (and common sense) says you need high temperature plastic sleeping for the resister and ptc wires. None comes in the kit. You can order ptfe from RS but it comes on long reals and is expensive. I stripped sleaveing from an RC car battery pack for the resistore and stripped sleaveing off of a low voltage light fitting for the ptc. I'll take a picture later. I didn't use the crimps. I soldered the ptc leads and used the metal parts from a 5amp electrical choc block for the heater

TCNeal Wrote:
-------------------------------------------------------
> Hey all, glad to see some others working on the
> same project as I am! I've also finished the frame
> and mechanics, just have to wait on a crimper
> before I can get started on the electronics.
>
> MotoBarsteward, or anyone else who has recently
> built it - since the instructions for this kit end
> before the electronics, any advice for those of us
> about to dive in? Also, what pieces did you use to
> go about mounting the heated bed to the aluminum y
> plate? Is that what the hex posts are meant for,
> or did you use some of the longer bolts with a
> number of nuts in between?

Hi,

i just used a bit of the Kapton Tape to insulate the parts on the hotend... this works very well.

I also replaced the wires for the hotend and board, i used an old power cable. I think thats a good idea in general.

My machine is working well now... trying to get best print quality possible