Re: The Progression of Kit278
January 17, 2014 11:47AM
Dieter

For now I am all about functionality and getting parts ready for the other machines. But I will definitely check to see if I can go 0.12mm or 0.06mm. Improvements every day.

3D-ES

OK, will try the retraction. I think those little blobs are also messing with the layers. When one happens the next layer sometimes looks that it has to go around it.



But for now I am happy and can continue with the parts for my LDI and 3axis router. The parts are now functional enough.
Re: The Progression of Kit278
January 18, 2014 07:49AM
I am giving up on the PLA X-carriage. Now attempting print in ABS.

The problem is that with a wide area print the table needs to stay 110C for much longer than e.g. the small parts I have done so far. Thus, after a while printing, the head sags again.

Another thing that is now acting out is the extruder. First that little clip, that holds the bowden started popping out. Whatever held it in is now not keeping it in. Also, the extruder gear is slipping. I lost a print because it just could not feed anymore. I am thinking that the same heat that sags the x carriage is causing accelerated fatigue in the extruder. Will let you guys know what I see when I open it up. But from what I understand is that if the head can sag then so will the friction eat away the PLA on the inside of the extruder.
Re: The Progression of Kit278
January 18, 2014 08:03AM
As feared, just about everything PLA is deteriorating on the head and extruder. The PLA backwash part I printed is loose, the extruder gears are running at an angle and even the bracket holding it sits around 5 degrees+ to the perspex. Must reprint all a.s.a.p to ABS.

I think the ABS is now slipping inside the extruder. I first picked it up when it battled to feed the black ABS filament. This filament is not 1.75mm (just under it) and the extruder cannot feed it. But the printer is still working moderately OK. Should be able to salvage.
Re: The Progression of Kit278
January 18, 2014 08:27AM
Hi victors

Thanks for the continued feedback - we never printed much ABS, and only did it in a relatively low ambient temperature (a British Autumn/Winter) so didn't experience the problems you have had. Our focus has always been PLA printing, as results are generally more reliable.

I suppose it isn't surprising that the extruder is deteriorating, sat over the hot bed, immobile and without much air movement. Possibly relocating it onto the Z axis vertical arm would be another option, though you'll need a longer Bowden tube. However, I'm surprised that the extruder is slackening off it's extrusion pressure so much. Have you checked the teeth of the hobbed insert for chewed up filament? Is there an increase in extrusion pressure (filament catching in Bowden tube, for example)? Another problem might be how hot the extruder motor is getting; I think they lose torque if they get really got (over 60C), but then the PLA would be very soft by then!

How much heat ends up in the aluminium extrusion? If you're printing in a high ambient temperature environment as well, the extra heat from the bed might be heating pretty much everything up.

Ian
RepRapPro tech support
Re: The Progression of Kit278
January 18, 2014 08:28AM
Victors,

Having built my own hot end and played around a bit and looked at heat dissipation and looked at the wiki on various head designs and ideas, seems the guys on ebay with the whole aluminium extruder drive and hot end in one seems to be the way to go for ABS. Problem is it runs though on a dual slide unlike the Ormerod, so I am not sure if one can adapt it. Obviously converting everything to aluminium is well possible but probably not feasible. I assume changing most of the parts to ABS may be your only quick fix. Should last as ABS has a much higher malleable point I think than PLA.

Dieter

Ormerod #257
Re: The Progression of Kit278
January 18, 2014 08:41AM
Ian

Ambient 31C (door is open, no air con, typical Africa temperature)
Extrusion motor temp.: 46C Even the Y motor, which I am forcing to 1000mA, is sitting at 46C

Extruder cavity clear, no crap inside.

Since my last mishaps I keep the Z elevated to at least 10 to 12cm and only preheat to 80-90C. But the deformity is now quite visible on the x carriage (with all my heat gunning and messing around.

But the "bend out" of the extruder is now quite visitble. I am not stopping it now. Pushing in filament by hand if I have to. It is halfway with the X carriage. Next print will the be extruder drive block and then the gears.

BTW, the head mount that I printed in ABS is still behaving. With the new ABS parts I should effectively be printing in an equivalent environment of at least -10C.


Dieter

I will get this thing MOFO thing to work ;-) Inbetween all this problems I am already halfway printed though my Z axis for my LDI machine.

But the users should be aware when printing ABS. It will cause a headache or two.

FIRST BIG TIP when printing ABS. Keep the head up high (away from 110C) until ready to print and don't leave it at 110C.

It does look promising reprinting in ABS, but then you have to be able to can print ABS ;-)
Re: The Progression of Kit278
January 18, 2014 09:06AM
To be fair, most printers printing ABS all the time, that have printed PLA parts, will have this problem. Some will be worse, because the extruder is mounted on the X-carriage, often off centre, so the weight causes the softened carriage to deform. Our mono Mendel is pretty good, as the x-carriage doesn't have the same amount of torque on it as the Ormerod, but even there I'd recommend replacing most of the printer parts with ABS versions if printing solely in ABS, and all of them if you're going to put the printer in a warm chamber. You probably don't need to do this, with your lovely warm environment - I'm sat here with 4 layers on, and still a cold nose and feet!

I'm sure I've pointed you at our ABS printing guide for Mono/Tricolour Mendel before, which discusses these issues: [www.reprappro.com]
I'll be more specific with the Ormerod version.

If you print a new extruder block, the first check to do is that the filament passes through the block smoothly. You shouldn't have problems with this in ABS, but it's the test we do, so you should too. I guess you can't check the hobbed insert teeth, as you're printing at the moment!

Ian
RepRapPro tech support
Re: The Progression of Kit278
January 18, 2014 10:10AM
Ian

angry smiley

Sorry to say but you seem a bit defensive. I am just trying to sort out all the problems on a system that I bought from RS that stated, 2 hours build time, PLA and ABS and many more. Frankly I don't give a flying ^&%$% what the Mendel can do or not do. I responded to an advertisement and bought $100 worth of ABS (which is the material required for my project) and now I must learn with the printer cannot actually do the job. I am sitting with a 2000W heatgun remoulding PLA with my bare fingers because the thing turned to snot.

This product can either be a success for RRP or a major disaster. Most people only got to printing their snowman.g. Wait until they try to print blocks of plastic and the thing turns to junk.

I also design products and I also export to other countries. In some of my systems I have to install heaters and in some design for 85C+ (where you can cook a steak on my computer box). So I understand it gets difficult. The thing is here that the Ormemod has been sold with a string of specification that we now need to hear does not really apply to this system. So your focus should not be to tell us what now cannot be done but find ways to to get the system to do as advertised. I paid more for this machine than my down payment on my house or all 3 of my cars together. At 500 pounds for the first 500 units it equates to 4x 4 bedroom houses in good areas here in South Africa. What would you do if you buy a car, with a top speed of 200km/h, and then you find out later it is dangerous to go faster than 60km/h?

I am now at my 3rd attempt of printing the X carriage. The current X carriage is now so badly damaged that I have to get it fixed. If this 3rd attempt fails I will print it with the remaining PLA and then try again on ABS. And I am also rushing against time. I have promised Bombardier (in Derby) a prototype active RFID demo by Tuesday (in ABS box demo-ed at the Midrand SA branch). If I can't get that built by Monday morning I then have to go print it elsewhere. Some buy this as a toy. I actually want to make some money from it.
Re: The Progression of Kit278
January 18, 2014 10:36AM
Sorry, but I'm not getting drawn into an argument about perception. My job is to try and give you the information you need, if I am able to. I pointed you at the ABS printing guide (admittedly, from our Mendel printer, and all that is available at the moment) early in this thread (the ninth post), and the problems of printing ABS on any printer built from PLA parts are clear from that.

Ian
RepRapPro tech support
Re: The Progression of Kit278
January 18, 2014 11:19AM
Ian

I also don't want to start an argument. But I cannot help smiling over here. RS made promises RRP apparently did not sign up for. I can understand that if I was part of the RepRap community that I would know $%^ everything about everything and the improvements from Model A to B to C can be seen as awesome by those involved. But until December I did not know anything about RepRap. I did not even know how to pronounce it. I got my 13 year old son to go read up about it and let me know what he thought. Then I showed the ad to one of my clients and he got excited. He also did not know RepRap but knew how 3D printers work.

Now, Ian, this is now your "new" market, newbs who just want to print. Within your RRP community everybody knows the difference between T2.5 and GT2, but the new bunch of clients, like me, just came in to buy a 3D printer for a good price. Now you might be upset with me being a bit rough with you, but I am the least of your problems as I have a few brain cells, can work a drill and I can hopefully figure out how to fix this so far south on the planet. The problem is that many of the "new" members of the RRP clan don't know the jargon or know to look for the "small print" on another unit's specs.

My (and other's) problem is this: Yes, the Mendel's ABS thingy states that the upgrade for the belt clamps should be the first things you print. I only really realized that when I almost picked up the head lying on the heating bed. Lucky I have a heatgun and can handle the pain pushing hot plastic back into position with my fingers. So the problem is that getting the printer to print the required ABS parts, that need ABS parts to start with, after there might be some damage and being far away from your offices makes it, well, very difficult to print large ABS parts (for replacement). I know there are people on the forum who has printed ABS without a problem but then there are people like me.


Can you create "Sticky topics" on this forum. This should contain a quick view on things you don't want to get bugged about, e.g. "All parts are PLA, not ABS" and "General warnings: (1) RS markets the unit as capable printing PLA and ABS, but it can only print ABS with several modification steps". Links to latest firmware.

Ian, so sorry if I offended you. I just generally speak my mind and this issue is causing me physical, mental and emotional pain.
Re: The Progression of Kit278
January 18, 2014 11:48AM
Hi victors

No problem, I avoid confrontation so things don't get too personal! I also understand the frustration that users have, we've all been there, and I get to hear about it more than most! With 20:20 hindsight, it's easy to tell you what you should have done, but that will only tend to infuriate you further. You are also ahead of our curve, so it's rather uncharted territory - I have been watching this thread with great interest, seeing how you get on. If there's anything I felt I could contribute, I have. Should we have tested [insert anything you can think of here] thoroughly before release? Yes. If you need anything from me (replacement parts, any specific information) just ask, and I'll do anything that is within my power. The main problem for you is the delivery time to South Africa.

I'm not an admin on the forums, so can't sticky topics. Also, I probably wouldn't sticky this specifically, as (from experience) it's a small subset of people that will end up printing with ABS. I think a sticky thread, probably locked, would be a very useful addition, mostly to direct people to correct information. It would contain general information, rather than specific troubleshooting, an Ormerod-specific version of this, perhaps: [forums.reprap.org] (sticky in the 'General' forum).

I appreciate all this doesn't help your current situation, and the time constraint you are under, for which I don't have a solution, unfortunately.

Ian
RepRapPro tech support
Re: The Progression of Kit278
January 18, 2014 04:54PM
Quick feedback from tablet...hate typing on it!

After 3 prints got x carriage printed in ABS. Old PLA one now dead. Sacrificed to make the new one. Result: Friggen awesome! Head now level, belt tighter than ever and prints look good.

Then printer extruder. What a mission. Original battled to grip filament. It actually looked perfect but somehow the expansion probably added microns between gear and bearing. Now it also extrudes the faulty 1.5mm. Just printed a gear with it. Looks good.

So:
1. Heat is bad for both head/carriage and extruder.
2. Reprinted parts seem to improve print quality.
3. X belt tensioned much easier on ABS. With PLA the gap widened and it would not grip the belt anymore.


Next: Getting the bed as flat as possible. Tomorrow I am making a 100mm x 150mm print.
Re: The Progression of Kit278
January 18, 2014 05:07PM
thumbs up
Pictures?

Ian
RepRapPro tech support
Re: The Progression of Kit278
January 20, 2014 03:25AM
Ian

Pictures. Will do some soon. I usually take pictures with my cellphone, but the interference usually crashed the Duet, so I don't take it into the lab (yet).

Progress:

1) The ABS X-carriage is still straight as can be. I now leave the bed on at 110C and this keeps the print from warping/coming off the bed.
2) New ABS extruder also still works like a charm. It is still an ugly print because I had to manually push the filament in when it stopped feeding. So it might be ugly but it is very functional. Will print a new one soon. The problem with the old one was that the PLA weakened, and as the filament pushed through it obviously pushed the bearing and screw to the side until the 1.75mm hobbed roller could not grab onto it. Now this is a nasty problem to solve once you don't have a feeder, because you need the feeder to print. Lucky I redid mine just in time.
3) I printed some gears. Came out perfect with default SlicEr settings.
4) I downloaded your pulley SCAD model and designed a 54 tooth T2.5 pulley. Beautiful. Problem was that the black ABS filament is faulty. It varies in thickness but is nominally 1.5mm (which the new extruder handled with ease) but failed at the 15mm level when the diameter suddenly dropped to 1.2mm. I am taking that roll back for replacement. But I played with both soft and hard T2.5 belts and the teeth fit perfectly into the belt. And this was with default Slic3r settings (i.e. no slow speed or any other enhancements). This was a moment for rejoicing because I need several 100 tooth pulleys and the local supplier charges around $70 each. For that I can buy nearly 2 1/2 rolls of 1kg ABS.

5) I still need to build something to help me level the bed. I got some longer screws. Will come up with something simple I hope.

Thus, after much pain and agony, I am now successfully printing ABS. I am not writing off PLA (as it prints like a dream compared to ABS) but I can now do both. I have to show my new RFID enclosure tomorrow and I think I should have no problems with that tonight.

Happy printing.
Re: The Progression of Kit278
January 20, 2014 04:17AM
Quote
victors
Pictures. Will do some soon. I usually take pictures with my cellphone, but the interference usually crashed the Duet, so I don't take it into the lab (yet).

Try flight-safe mode?



Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: The Progression of Kit278
January 20, 2014 04:29AM
Quote
victors

5) I still need to build something to help me level the bed. I got some longer screws. Will come up with something simple I hope.

my bed rest on 3 points, have springs under two of them, fast and easy to adjust, shorter screws in the two front corners so not to drag in the holes in the mdf downunder

<------ spring

Erik
Re: The Progression of Kit278
January 20, 2014 07:05AM
DC

I always forget to put the cellphone in flight mode. I get reminded about that fact when the Duet crashes ;-) So I just leave it elsewhere. Oh, the Duet still crashes with the Xytron PSU, so it is not PSU related. Want to still print test job from SDcard only to see it it crashes. Generally it is one loom that will pick up the EMI. Will eventually find it.

Erik

Will look into that. I need to check what kind of springs I have in stock. The crap is that this like tuning a dining room table on 4 or more points. Your 3 point method seems much more logical. (Now I sound like Spock:-)
Re: The Progression of Kit278
January 21, 2014 05:24AM
ABS Extruder

Last night my one print stopped extruding halfway. I have been using a filament that varried between 1.75mm downto as low as 1.2mm. The extruder could not feed this, so I took it out. I replaced it with another one that was more consistent. After about 30 minutes the extruder did not feed the filament anymore. The problem was that the ABS extruder (now much stronger) did not have the correct spacing between the hobbed element and bearing. It happily fed the filament (on its own) but pressed it flat. Eventually the, now flatter and wider, filament experienced more friction in the Bowden tube. I had to take tube off and basically pull the filament out with pliers. I tested it again with the same piece and confirmed that the filament could not really fit inside the tube. Checked it again with unfed, virgin filament and it passed through with no problem. Even extruded a bit just with hand pressure to make sure the nozzle was OK.

So I took the extruder apart. I shaped the bearing seating (hobbed roller side) with a knife so that the space was just enough to grip the filament but did not deform it (and also not slipping under pressure). The end result was a perfect feeder.

What I don't know is if the design is slightly out, does ABS effect the print or did Slic3r fed too much filament making the holes too small. I am going to reprint the extruder again and just check the new one has the same problem. I am keeping in mind that I did print this with an already fudgy PLA extruder. If so the fix is a few minutes worth of filing and cutting.
Re: The Progression of Kit278
January 21, 2014 01:24PM
I'm guessing here ...

Plastic shrinks as it cools, so I suppose to get really accurate dimensions you have to scale your 3D model up by a small constant factor. Nothing I have made so far needs such precision, so I've not gone into it. I guess the RepRapPro STL is scaled for PLA shrinkage, and ABS has a different shrinkage (I think it shrinks less than PLA, BICBW). Having said that, the ABS extruder I printed yesterday has worked fine today (about 5 hours of printing ABS so far). The filament channel was a bit tighter than the supplied PLA part, but still loose enough to be no problem, and hopefully it will get looser with wear. I did have a problem once with the original extruder slipping, but cleaning the hobbed bolt in soapy water fixed that - I think it had got slightly clogged with plastic dust. I've not looked at Repetier much, but I read somewhere that it is capable of scaling an STL model.

Dave
(#106)
Re: The Progression of Kit278
January 22, 2014 03:39AM
Dave

My problem seems to be a combination of mishaps. I have printed new parts since and they are also within spec. The problem seems to be the fact that the PLA extruder was failing, laying down too little plastic in some cases and then I had to press it in by hand as it stopped. I actually took a black marker and kept on marking the filament as it it moved (used white)... And I sat there for the 2 hour+ exercise! If I saw the gear turning, and no filament movement I would gently press the filament in by hand. This happened more regularly than not. The result was "power feeding" in certain places. This means intentional swelling! I checked it against the PLA version and there is even more space now than what I have already cut away from the ABS version. So I think the RRP design is sound for both PLA and ABS. I just need to now spend some time and print a proper one. But at least I now have spares.

So for those who want to print something worthwhile in ABS start with the X carriage and extruder, and then make a few gears as well. My PLA gears started to show some wear and tear. I first made the big gear in ABS and installed it, but the ABS against the small PLA gear definitely showed more stress on the little one.

I spoke to another person here in South Africa, with a mofo big 3D printer (the only other person close by I know now), who has a machine that can print nylon. I am going to contract him to print me these critical parts in nylon. He also makes hot-ends, that if modified, will fit the Bowden tube (although it appears he supplies PTFE tubing as well). His hot-ends can run upto 300C+. Then I should be able to print nylon and polyprop myself. BTW, the hot-ends are around $60 to $70:

"Hot End, fan & shroud, 0.3mm nozzle, 400 mm low friction 4mm tubing, connectors & pins, heatshrink.

Not included is a 6mm Heater cartridge and thermistor

"

-----

Additional cooling.

Seeing that this machine is already a professional noise generator I am thinking of making it even louder ;-)

Communica (South Africa) sells little 40mm x 40mm x 10mm fans, defined as medium speed (which means slow) and cost between $4 to $9. I am going to print some parts to attach to the X and Y motors for additional cooling. I know I am way below the motor temp spec as I measured them at ambient of 30C to run only to 49C. But it seems that the Y axis already requires a bit more "oomf" to not skip steps. I currently have it 1000mA. I have also found skips on the X as well, especially when I printed the gears too fast. Now the X stays stable over the entire build so I am not too worried about that, but the Y axis takes on more weight as the part grows. So I expect that I might need to "up" the current on the Y again when printing large parts. I don't know if anyone has printed really large parts, like 500g+? It is nice having a 200x200 bed but as the part grows it gets a lot heavier. So I don't know if the Y axis will still be able to do fast changes when loaded. Remember F=ma (force = mass x accel). Thus if the acceleration is reduced it should handle more mass. At some stage the Y motor will lose the battle. The quick test will be make a small, intricate print and then stick weights on the bed and see how it goes. My theory is that the X will need a bit more juice and the Y maybe more than the 1000mA. So adding fans to these motors (with maybe a bit of extra heatsinking) might just extend the life of the motors. ...and add some more noise ;-)

I now edit all my Slic3r Gcode files and change the currents during a print. There is no need to kill it when the print is still small. So at a certain Z level the currents can be edited to increase and then switch off (to normal) at the end of the print. Remember the motors still draw current while it is standing still.
Re: The Progression of Kit278
January 22, 2014 10:13AM
Well, having been bitten by the 3D printing bug, I will probably design & build a completely different, beefier machine during the year as a hobby, using experience I'm gaining while using & modifying this one. Probably basing it on one of the many RepRap proven designs. The problem with mass-produced goods is that the designer is constrained by having to save pennies on each part (as I know very well). A one-off build has fewer penny-pinching constraints, and if a better part costs a few dollars more, it's a no-brainer to spend the extra. You can also use any part that is currently available without having to worry about it going out of production in 2 years time, which is another headache for commercial designs. It will be possible to use more powerful motors and over-design for longevity. There's also the possibility of fitting a rotary encoder to the shaft so missed steps are detected - or even using a DC motor with rotary encoder instead of steppers.

The main design limitations I see in the Ormerod is the fact that the X-axis is hanging in mid-air at one end - any small wobbles are therefore magnified at large X positions (and I see it visibly wobble in use, no matter how tight the Z runner bearing). Also the extruder is hanging on a single bearing on that axis. My Perspex has a very slight small hollow at one place that the bearing rolls over, which is faithfully reproduced in all my prints.

Dave
(#106)
Re: The Progression of Kit278
January 22, 2014 11:17AM
Quote
dmould
Well, having been bitten by the 3D printing bug, I will probably design & build a completely different, beefier machine during the year as a hobby, using experience I'm gaining while using & modifying this one. Probably basing it on one of the many RepRap proven designs. The problem with mass-produced goods is that the designer is constrained by having to save pennies on each part (as I know very well). A one-off build has fewer penny-pinching constraints, and if a better part costs a few dollars more, it's a no-brainer to spend the extra. You can also use any part that is currently available without having to worry about it going out of production in 2 years time, which is another headache for commercial designs. It will be possible to use more powerful motors and over-design for longevity. There's also the possibility of fitting a rotary encoder to the shaft so missed steps are detected - or even using a DC motor with rotary encoder instead of steppers.

I'm not sure you would gain very much. The steppers work reliably for me, except when there have been firmware bugs that cause them to be driven too fast. The only penny-pinching I see is in the selection of a low-end ATX PSU - but the ones supplied appear to be adequate at least for PLA printing. Because ATX PSUs are so standard, it is a simple matter to substitute a better one, such as the Corsair CX430M that I am now using.

Quote
dmould
The main design limitations I see in the Ormerod is the fact that the X-axis is hanging in mid-air at one end - any small wobbles are therefore magnified at large X positions (and I see it visibly wobble in use, no matter how tight the Z runner bearing). Also the extruder is hanging on a single bearing on that axis. My Perspex has a very slight small hollow at one place that the bearing rolls over, which is faithfully reproduced in all my prints.)

Then why not replace the Perspex by a flatter and perhaps thicker piece, or by aluminium? I think it is necessary for the extruder to hang on a single bearing, so that if the print goes wrong and a glob of plastic gets extruded, the head can ride over it.



Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: The Progression of Kit278
January 22, 2014 11:20AM
I've been running with a bearing on the front and back for some time now (the front bearing support has some flexibility, but so does the bed and the X arm), both bearings stay engaged fine, and the front roller seems to help in ironing out bumps, rather than stalling on them.
Re: The Progression of Kit278
January 22, 2014 01:43PM
Quote
dc42
I'm not sure you would gain very much. The steppers work reliably for me, except when there have been firmware bugs that cause them to be driven too fast. The only penny-pinching I see is in the selection of a low-end ATX PSU - but the ones supplied appear to be adequate at least for PLA printing. Because ATX PSUs are so standard, it is a simple matter to substitute a better one, such as the Corsair CX430M that I am now using.

PSU, SD card, Perspex instead of aluminium parts, MDF & plywood bed, stakes instead of shrouded headers on the PCB.

Quote
dc42
Then why not replace the Perspex by a flatter and perhaps thicker piece, or by aluminium? I think it is necessary for the extruder to hang on a single bearing, so that if the print goes wrong and a glob of plastic gets extruded, the head can ride over it.

Yes, I'm fine with the hanging idea - I'll save changing to aluminium for my next machine.

Dave
(#106)
Re: The Progression of Kit278
January 27, 2014 05:01AM
I reprinted yet another ABS extruder. Works great now. But below is my new Z axis for my PCB printing/drilling/laser machine (I keep on adding more functions as the feeling hits me). Currently I can hook a Dremel, UV and blue laser on the head. The base is 8mm thick (150mm x 100mm) and the table 10mm thick (100mm x 100mm). Combined those two took almost a whole 24 hours to setup and print. The bearings are 6mm. For them I printed PLA pillowcases. The rests for the rods are the red ABS I battled so much with a while ago. These pictures should be higher up in this thread.

Not show in this photo: (1) Nema17 bracket and motor, Dremel brackets (2x), 5mm threaded rod/zero backlash nut (with fair amount of friction still), bracket for nut and mounts for the lasers.

The holes were made slightly smaller for the screws to cut thread. 4mm I took down to 3.5mm. 3mm down to 2.7mm. It takes a fair amount of effort to get the screws in so I think they should last a long time.

The table moves without any play in the other directions. Perfectly stiff. Motion in the bearing direction is smooth. And this was straight from the printer. No parts were modified. I actually assembled the whole thing this morning, in bed, with 2x screw drivers.

The 150mm x 100mm print was so far the largest I have done. Realistically I think 170mm x 170mm might be the biggest that one can go. Those pesky clips are in the way. I would also not make new large prints as solid as this one. While printing it started lifting up slightly on the edges (so little I had to look for it) but after it cooled down if developed a slight bend in the opposite direction. Maybe with a few ribs? I printed the entire thing at 110C. It is a fine line of losing the print to curling up edges and overcooking it.

I will post more pictures as I get it assembled.




Re: The Progression of Kit278
January 27, 2014 05:06AM
Those parts look great! Not sure I would want to make the bed out of ABS, but I guess you can easily bolt aluminium sheet to it when necessary.

Regarding those pesky clips, see [forums.reprap.org] for an alternative that only takes up 3mm at each end.



Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: The Progression of Kit278
January 27, 2014 10:01AM
DC

This is luckily for a "cold" application. This Z axis basically holds a drill, and 2x lasers (UV and Blue). But trust me, that bed bends with difficulty. The drill runs at 37000rpm so it won't even feel the pressure and the lasers, well, light has no force effect. The only force will be from the PCB router bit, but I will have to see if that will be bad or not. If it looks like it is going to bend too much I will screw an ally T-bar onto it. But as a plastic, straight from CAD to Ormerod, it works pretty cool.

But just the look and feel makes this thing way sturdier than the Ormerod's frame (or lack of it). And if I ever decide to build a 3D printer based on this concept it should be stronger. The 6mm rods are OK for these short strokes. I only need to lift it high enough to be able to swap a drill bit. But using mild steel as a base, these red standoffs and thicker rods would definitely work. 12mm still looks like the minimum for e.g. a 30cm length.

RepRap should bring out a 50% kit. All the motors, controller, plastic printed parts and then you must locally source linear bearings, rods and PSUs (or something a long those lines). In fact they should have a checklist and just select, based on need , what you want. E.g. locally I can get linear mechanics, motors, controllers but not extruders, hot ends and printed plastic parts (not having e.g. an Ormerod). Currently I am looking to buy that hobbed element, in extruder, but nobody stocks it over here.
Re: The Progression of Kit278
January 27, 2014 10:13AM
Quote
victors
Currently I am looking to buy that hobbed element, in extruder, but nobody stocks it over here.
download one from thingiverse (check out the video on the page) smiling smiley [www.thingiverse.com]

Cheers

Ray

[edit] actually it might be better to centre the point of the tap (or the centre hole if it has one) and leave the shank floating then use a power tool to do it)

Edited 1 time(s). Last edit at 01/27/2014 10:18AM by rayhicks.
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