I am still in the process of making the printer as perfect as it can be with his construction.
When i first build the printer i already tried to make him perfect till a certain degree.
After the first disappointing print i immediately started searching for issues.
these are the issues i found that stand in the way of producing satisfying prints.
*Bed guide, had to adjust it several times and even had to bend the alu plates a little bit to make the operation smooth.-done-
*gears for the belt, they are bored way off center, drilled them out to 6 mm and pressed some massif alu in them. Made a bushing so i could clamp on the the gear it self and not on the flanges. Drilled it with a precision 5 mm drill. Now they are perfect.-done-
*Bed itself, known issue that it bulges in the middle. No way to make that straight, only a mirror will do the job. Not fond of the extra weight on the moving bed.-done-
*Extruder leak, although i torqued it to 3,5 nm i still had a small leak. cleaned it and put a little (special)compound on the threads to stop the leak and torqued it again to 3,5 nm.-done
*The really bad thing is the threaded Z rod, no way i could get the Z motion to run smooth. on motion i could always see an uneven movement.
I put the rod in a lathe together with the mounted coupler and made sure it was as straight as possible, but once i put it on the motor there was still some movement.
I decided to order a trapezium threaded axle. Haven’t got it yet.
*While waiting i decided to test the smoothness of the Z guide, this was also not smooth. After some measuring i got the distance between the rods on the downside the same as on the upper side. Did that by fastening the upper mounts a little extra. But measuring where the wagon sits i measured a distance that was almost 0,8 mm smaller. After loosening the bolts i still measured a smaller distance. Only after moving the right side bearing holder up and out a little i got the measurement to be almost exact on the whole rod. Have to decide if i bore out the holes or file out the holders.
*I noticed that some of the linear bearings do not run smooth even if i single test them on the rod. I have no solution for that yet.
All in all i hope to get better results if i have fixed all the above issues.
Made a new motor mount,top mount and the mount for the nut.
Made them out of aluminium, the motor mount out of 4 mm alu sheet and the other mounts out of solid alu.
I also bored the mounting holes for the lineair bearing holders to 6 mm. now i have a smooth travel and the bars stay at the same width during travel.
I have printed a calibration cube and the form was good.
I am now printing a spool holder.
I already made an extra motor holder for an second Z-axle but i dont know if i will ad it.
And if i ad it, if i will run it from an extra motor or drive it with a belt from the first axle.
I did remove the top nut and bearing.
Even though i can’t see the threaded spinlde wobble/swing at the top, it does seem to affect if i put a bearing on top.
There is a visible pattern that corresponds with the threads, in my case 2 mm per rev.
Today i printed a fan duct and noticed the pattern again.
While printing i removed the top nut and bearing, after that no pattern is visible.
Are there others that have removed the top bearing?
I use a 10 x 2 trapez, i see others use a 8 x 1,5 maybe that spindle is a little more flexible so the extruder doesn’t move with the spindle.
I also seen someone use a 14 x 4 trapez, that is absolutely not flexible but very rigid.
And when straight the extruder also won’t move.
I can’t really figure out where my problem comes from.
But hey, leaving the top loose does not give me other problems. So i think i will leave it like this.(although i hate that i can’t get it right)
[quote=“2stimpy”]I use a 10 x 2 trapez, i see others use a 8 x 1,5 maybe that spindle is a little more flexible so the extruder doesn’t move with the spindle.[/quote]they both have advantages and disadvantages.
The TR10x2 will result in 0.01 mm per full step on the Z axis, which gives you the freedom to chose all “usual” layer heights like 0.2 or 0.25 mm. The load on the motor will be slightly increased because of the larger pitch and diameter (increased friction), but that shouldn’t matter too much.
The TR8x1.5 on the other hand fits the original bearing and also the widely available 8 mm flex couplers, so it’s less effort to get parts (if not already present), I presume. However, the 1.5 mm pitch comes at a price: one full step corresponds to 0.0075 mm. Thus, 0.2 mm or 0.25 mm layer heights are not divisible without remainder. If you want to keep it to two digits of precision, you can only adjust layer heights in 0.03 mm steps. For the printer it doesn’t matter - but if your stomach hurts when setting 0.18 or 0.21 mm layer height, you’d better not use 1.5 pitch …
By the way, the printer here runs fine with an overdetermined TR8 rod: one 608 on top, one on the bottom, alu bracket for the RG7 nut and finally an alu flex coupler to connect the motor, so that’s four (three and a half perhaps because of the ‘flex’) constraining points. It shouldn’t work, but it does. Since all the axial load is taken over by the bearings, the motor can even be mounted on it’s stock alu bracket.
It is very important to have a straight z axle.
I did readjust some things and put the bearing on top again.
I also printed a fan duct and modified the z height adjustment.
After getting this done i printed the board cover.
I think it came out pretty nice
There are still some ripples but i don’t think they are related to the z axle because they aren’t regular with every rev.
I noticed 2 other issues.
The cover is bulged at the top(bottom on glass bed) and i notice that the first layers that are printed are a little wide, like there is to much material printed there.
That is probably also the reason why the writing is not perfect.
that bulging, that is your print that warped. Is it PLA or ABS? EIther way, try increasing your bed temperature and if at all possible, covering/enclosing your printer. The warping is due to the plastic cooling down and contracting too soon. ABS is much more susceptible to it than PLA, but Ive had large PLA prints bend upwards as well when my bed was too cold.
I also use that tape. The tape was already getting loose from the mirror because the print started to lift at the edges.
In the middle the print was still sticking very well.
I read somewhere that people set a high temperature for the first layer for instance 70 c, an after the first layer drop it to 50 c.
In Cura they made a plugin for that.
I made myself a new bed.
The mirror work fine but i hate how i have to clamp it to the bed.
I have made me a few of these alu plates and i fix the plate to the bed with bolts so that i never risk hitting the clamps.
I only had that issue once but now it wont happen again.
I still have to use something to make the print adhere to the alu plate just like on the mirror.
Also mounted the controller housing with the fan and filter in place, and already mounted the extra Z-motor.
Have to make the holders for the upper bearing and the nut.
As you can see, like a lot of you i can’t stop making improvements.
One thing i don’t like is the extra noise created by the fan duct i use at the head. Also the fan in the housing isn’t that silent although it is a high quality unit.
Hello, I suspect my k8200 in the mail anyday next week I like your modified housing (with the fan in it). Do you suspect that the original housing by velleman would cause overheating?
I like your work so far! My first improvement would be the Z-axis stabilization. I allready have a design that I can print out the moment the printer is up and running
I will be following your thread for further improvements!
[quote=“KLucky13”]Hello, I suspect my k8200 in the mail anyday next week I like your modified housing (with the fan in it). Do you suspect that the original housing by velleman would cause overheating?
I like your work so far! My first improvement would be the Z-axis stabilization. I allready have a design that I can print out the moment the printer is up and running
I will be following your thread for further improvements!
Keep up the good work.[/quote]
You will have lots of fun building it, i can only say, take good care an make sure all the the linear bearings/guides run very smooth.
And make sure the gears for the belt are proper center bored.
The Z- is also a very important part to get good prints.
I put an fan in the housing just for safety, to be sure that when i run 2 motors for the z-axles on one driver, i won’t have over heating problems.
The downside is that it makes some noise, so i think i will put a switch in between.(it would be nice to let it switch on at a certain temperature)
The fan nozzle also makes to much extra noise for my taste, without those extras the printer was rather quit. Now it isn’t.
In the meanwhile i have done some upgrades again.
I bought the standalone controller and the led ring for the printer.
It all works again after an firmware upgrade to marlin v2 from the velleman site.
Only thing is(like asked in the software forum) i don’t have values set in the eeprom settings anymore.
They are all set to 0, how can i set these parameters in the future.
see you use the painters tape on your ‘design’ bed. Might try with a kapton sheet. Works fine for me (on a mirror), even with ABS.
Found some @ EckerTech (CAN). Different sizes available.
Yes, I was going to try the kapton. Thanks for the link.
I must say that the first layer sticking has a lot to do with the starting height.
But what i dont like is the matte finish, is that nicer with the kapton.
If you use stripes of narrow tape (10 or 50 mm are common), you’ll see a residual structure on your part even if the tape is fixed exactly edge-to-edge.
A large sheet will solve this problem, but it’s a challenge to get it fixed without bubbles underneath (which again will be visible in the printed parts). The foil often is very thin, thus it easily deforms when one tries to correct a part that was already stuck to the surface.
I think I wasted three or four heatbeds worth of the 200 mm wide tape before I got the first one right (by using a printed support to keep it from adhering to the “wrong” places). Nasty stuff.
Kuraasy, I wil try the larger sheets of the kapton then.
Is it easy to remove the print from the tape? Can i print more times from one layer?
AÄronR, I like the ring, even though it is above the fan duct i still get enough light.
Of course it could be made cheaper but i did not want to waste time on it.
[quote=“2stimpy”]Is it easy to remove the print from the tape? Can i print more times from one layer?
[/quote]
for PLA glass and kapton are similar, with good adhesion at ca. 50 °C, and easy removal after cooling. ABS adheres much better on hot (90 to 110 °C) Kapton than on glass, but for some objects brim may still be necessary. Removing ABS was also possible without problems. E.g. for the thin skirt, I used a sharp scraper, which works well but also produced one or two defects in the Kapton (wrong angle, thus cutting instead of scraping off).
Once you get the tape on, you can print on it again and again. The “user-induced” defects limit the usage time much more than any kind of wear.
the kapton I mentioned is rather thick (0.23mm) and self adhesive.
If you apply the kapton with a soap solution it can be easily manipulated.
Just search ‘the net’ on how to apply kapton and you’ll find lots of usefull tips.
Worked for me, no bubbles. Just start by cutting the kapton to the right size first.
After applying, let it rest for a day or so. Maybe put some weight on it.
The first layer has a glossy finish. Same sheet can be used multiple times.
Just be carefull not to damage it while removing your parts. Just let the bed cool down after printing.
I like your modified housing (with the fan in it). Do you suspect that the original housing by velleman would cause overheating?
