Another Sintratec kit built

Hi,

I first saw the Sintratec kit at the Birmingham TCT show, a few weeks ago, and was impressed with both the machine and the group of guys involved with its production. I have just completed the building of the kit and am just waiting for a couple of missing parts before attempting the initial commissioning. Dominik pointed me at this forum and it is good to know there are others out there with which to share the ups and downs of low(ish) cost SLS printing. I do not intend using this printer commercially so it is quite an expensive hobby item but I am really looking forward to doing some interesting stuff.

Mike

Hi,
Wellcome! Nice to see aother guy here. I do not use the printer for commercial porpose, too. I have learned same interesting things and got same experiance with this printer.
One importand thing i have learned is not to connect the printer to the computer after a cleaning and changing something. Use an USB hub!
The results are very nice :-)

I am another hobby user with a Sintratec kit. I ran into a mechanical problem and put the assembly on hold for a while. I'm hoping I solved it but haven't had the time to return to the build.

rudschul, why is it necessary to have a USB hub in the circuit?

I've also discovered that the appears to be no US source of PA12 black nylon powder for SLS printers.

Hi,
that is nice to hear, that there are more people having a Sintratec printer. I come from Germany and i have to import the powder from Sintratec into the EU. Hopefully there will be a reseller avaible in Germany in future. I think if there is no reseller in US you will have the same import issues like me. I do not use the printer for commercial purpose. In that case for me in is no problem to order it directly at Sintratec. It takes about a week, if the dokcuments are ok.

If you have an short-circuit fault you will destroy your USB host controller. That is very bad. If you use an USB hub with short-circuit fault prevention you will not destroy your computer.
A short-circuit fault is possible if the cable of the of the IR lamps get contact to case. I have used capton tape to protect the cable. But the protection was not good enough. After some print and optimization the current goes through the capton tape.....
New version of the kit are better because they have an different IR lamp cable with protect i think up to 400 C. If you have glass fiber fabric cable you have the new one.
But after i have a short-circuit fault i have learned and will not connect the printer directly.

Thank you for the clarification. I do not have the wiring insulation you describe. I think I will delay my project completion in order to prevent the short circuit. I have located fiberglass high temperature insulation sleeves from eBay (US) and will place the order today. The US sources are not as well suited, I think, and are much more expensive. I wish Sintratec would inform the kit owners of these possible problems!


http://www.ebay.com/itm/600-Deg-C-Braided-FiberGlass-Tube-High-Temperature-Fiber-Glass-Sleeving-500V-/192003275237?var=&hash=item2cb44979e5:m:mA9TnFP888 wtov2QbqmYpow

Attachment 9797

Thanks rudschul & fred_dot_u for chipping in. Good to know about possible short circuits although my kit did come with, very long, insulated leads on the IR lamps. While waiting for the missing parts to arrive, I have checked, double checked and then checked the wiring again and I am still not looking forward to the first switch on! I love the mechanical side of things but electricity leaves me bemused as you can't see the stuff until the smoke gets out then it's too late.

I did point out to Sintratec that their video, linked on the first page of the 'Initial Commissioning', showed completely different wiring to the manual. I have been assured that the manual is correct and they are taking the video down - it didn't do my confidence any good at all.

I am surprised at the price of the powder when you consider the price of the raw material in pellet form. I appreciate it has to milled to fine tolerances but when you consider how much of this very fine powder, of all types, is used in the cosmetic industry, why is it so expensive for us?? Just do a search for 'Nylon 12 sls powder' , places like Alibaba has tons of the stuff if you want tons at a time.

Mike

If we had more builders/owners in a more concentrated geographic area, a bulk buy of a few hundred kilos would make sense, but shipping internationally really builds expense. The low volume alibaba people want US$110 per kilo in small lots, no less expensive than Sintratec.

Quote:

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If we had more builders/owners in a more concentrated geographic area, a bulk buy of a few hundred kilos would make sense, but shipping internationally really builds expense. The low volume alibaba people want US$110 per kilo in small lots, no less expensive than Sintratec.

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Agreed - the problem is when you want to experiment with different materials. It has been suggested that I go with a begging bowl to nearby, bigger sls businesses for a couple of kilos at a time. An alternative may also be Universities with 3D printing facilities. I'll see how I get on with the supplied powder first before getting too ahead of myself.

As you can see i bought the kit from Hugoes. He made the cabling and so on. It is the crowdfunded version. But right know i think i have build the printer twice. The electric cabling is right good. You can check as described without fuse. This helps a lot. On the other side take the right version of the manual. You see date when you extract the download.
Attachment 9800
At this picture you see i think the 2. version. The IR-lamps have the "bad" wire. But you have protection tube. I have no experience how good they are. If you are not sure ask Sintratec. They are helpful. If you have not finished to build the printer keep aware to close every corner where powder could be.
A very good tip from Sintratec was to use special glue you get with kit. Take q-tips to put the glue at the corner and then take every glue away so that you see the blanc metal. You do not have much time but it works really good. But very careful you will not get the glue away after some time. It is very hard to do after first use, but i have done it. It makes o lot things easier.
Keep in mind that you can reuse powder. Yes the powder is expensive but not so expensive as you think.
A bad print..z-direction makes problem. I hope i have a solution.
Attachment 9801
A good print:
Attachment 9802

rudschul, it is difficult to see the wiring in your picture of the lamp kit so I cannot compare it with mine. Mine has heat resistant, braided insulation on the leads and I have not used any other form of protection. In the kit there is a coil of spiral wrap, wire protector but nowhere in the instructions is this mentioned. Maybe someone at Sintratec can comment here?

I have sealed the powder compartments really well but did not remove every trace from the corners, leaving a very small fillet. It does not seem to have had an effect on the platform movement, it has always been a little stiff but smooth.

With the very regular problem in your Z direction, I would suspect a problem with the screw that drops the print area. It is difficult to say because there is no scale but if the regular gaps are the same pitch as the screw threads of the lead screw, it may suggest a link between the two such that every one revolution it may skip steps or make a larger drop due to backlash or problem with the drive. Just a speculation based on many years of CNC machining and leadscrew issues. Just ignore me if I'm way off the mark.

Mike

I had a problem with my Z travel on both platforms. I discovered that the bearings for the stepper motors and the metal "floor" that surrounds the bearings were not in good alignment with the holes through the rest of the structure. There was severe binding once the assembly of that section was placed. A good portion of the mechanism had to be removed in order for me to slightly enlarge the pass-through holes and to push on the bearing floor (stepper motor assembly) in order to remove the binding. I have not yet tested my modification since the re-assembly, however, so I cannot say how successful it was. There is enough freedom of movement that I can rotate the screws when previously I was unable. The manual does indicate careful measurement is needed, but a sharper note regarding clearance and alignment would have been useful.

Maybe they tightened up on tolerances because my kit lined up perfectly. I was quite surprised when I dropped the hat onto the core to see the leadscrews go straight through the bearings and into the motor couplers. With regard to ease of operation, I can raise and lower the tables by rotating the coupler by hand so I am hoping the steppers can operate reasonably effortlessly.

As i wrote i hope i have a solution for my z-problem. Sintratec told me that i have an old version of coupler. The coupler is flexible. Depending of the position there is sometime more force needed to move. Then the system is swinging. Now i have got an infexible coupler. We will see.... I think in the next day i will see more... I have to recalibrate my laser, because some screws get loosen. (laser holder :-() Losen srews seems to be the biggest problems with the printer. You tighten the scews. You print 2 or 3 times. some screws are not tighten anymore....I have a call with Sintratec about this problem. But i think we have not realy a solution. I is a temperature problem....
@fred_dot_u: my core is fitting very well to the had. The clearancy is very exacly to all parts.

Interesting what you say about the screws becoming loose. I did notice that there were no references to any thread lock throughout the instructions which surprised me a little considering the complexity of the build. Probably more important when you consider the difficulty in doing it retrospectively! With the temperature differentials during a print session, it probably shouldn't be too surprising, given that aluminium has one of the highest coefficients of expansion of all the metals.

Got me thinking now!!!

Your are right.
On the other side most connection are safe. The nut prefents loosing. Following positions have the problems from my sight of view:
1. Laserblock (very bad if you are cleanig the printer)
2. the sliding mechanism of the print and power chamber. The use special nuts but the conter nut gets loosen
3. the shelf of the printer ... not a real problem

Well, yesterday my missing parts arrived so I was keen to get them in and the construction finished. I double checked the wiring (yet again) and connected everything up and turned it on. So far so good as there was no smoke. Following the guide, next was testing the components - here I hit my first problem. The 'Apply Powder' seemed to partly work but there was a horrible noise of stepper motor driving against a stop. Quickly turned off the test and tried the powder compartment drive. No problem all worked as it should. Then tried the build platform and again, there was a problem and just a lot of noise from the stepper. It then dawned on me that the stepper making the noise was not the one that was supposed to be moving - I had the 'Apply Powder' and build steppers round the wrong way. Swapped the two motors and everything was fine with the three steppers.

Heat up worked just fine.

Laser testing - It took me ages to find the very small dot for the centre point and I had to fiddle with the galvos, lifting them out and rotating the two of them before I could see anything on the calibration pattern but eventually all was looking good. Then tried the pattern routine but all I got was a horizontal line with brighter dots on it that ran through the centre point. I traced this to the Y axis galvo not working. I turned everything off, swapped the lead from the X axis to the Y axis and tried again. The Y axis galvo was working so the fault must be with the Y axis driver. I still have to find where the fault is before reporting it.

Incidental problems -
I noticed that every time I turned the printer off, the software would hang and had to ctrl, alt, del to get rid of it and then re-load.
The reset button, next to the laser key, is constantly flashing no matter what mode or operation is being carried out. Is this normal?
The master on/off switch has failed in the on position such that I can no longer switch off the power into the machine at this switch but have to go back to the wall socket to turn it off.

Long post but I hope someone can help.

Mike

Further to my woes. It is now conclusive that I have a dead galvo driver.

I first swapped the power leads to both drivers to see if it was a power supply issue. No problem, power to both drivers.
I then swapped the X and Y at the motherboard - no difference other than the Y galvo now moved as expected.
Then swapped the final lead with the same result.

The only conclusion I can reach is that I have a dead galo driver.

The problem with the software hanging was my fault. I didn't realise the configuration window hides behind the main screen, when power to the printer is switched off, and wouldn't allow anything to happen before it was closed. So, just a dead driver and a faulty main switch to report to Sintratec.

That sounds not good.....
The Reset light has the same behavior with my printer

Yes, bit of a bummer - there was no smoke so I am guessing it was faulty from the start. I have sent a ticket to Sintratec and will have to wait to see how quickly they respond. The time it takes to respond has been a bit of an issue with, sometimes, up to three days before getting a reply. I have raised this with Sintratec so will have to see if anything changes.

As far as the build goes, I have been very impressed with the quality of parts and the fit and the fact that everything moves as it should, without any major tinkering, is testament to this. With electronics, as far as I am concerned, it either works or it doesn't and unfortunately, I have a component that doesn't work.

Apparently, good things come to those who wait!!!!!!!!

Sintratec sometime answer really slowly. I think it is an resource problem a lot of start up company have. If i think it take to much time to play the question and answer game with a ticket system i call Sintratec...
On the other side perhaps you got an secondary problem with your first electronic board. I have made the experience with the ir-sensor. It was not working correctly and makes o lot of trouble. If a had an electronic failure every time the ir-sensor was killed too. But for me it was very important to known me printer was working fine exept the measured temperature. Yeah and now my printer printing again.

Hi rudschul, I am absolutely sure there is not a problem with the main electronics board as I have wired both the X and Y galvos from both outputs from the main board and both work fine when put through the X galvo driver but neither of them work when put through the Y axis driver. Also, both power supply lines work okay so that only leaves the Y axis driver as the culprit.

We will see what happens tomorrow, if I get a quick response.

Hi Guys

I guess most of you already know me from the ticket system :) im following this thread for while now but wasn't able to reply until now.

i try to cover as much with my post as possible but if i forget something do not hesitate to point that out.

Powder
As for the powder I strongly discourage to buy powder from alibaba. First and most, we do not provide support for powders that isn't ours. The powder we have is optimized for our machine and laser as we use a laser diode ant not a CO2 laser as commercial laser sintering machines do.

Lamp cables
The lamp wires were a big issue. But we provide PTFE sleeves with the crowdfunding units and ceramic wire sleeves for all models provided outside the campaign. The incident with rundenz printer was a very very unfortunate chain of events which cause a short circuit.

response time for ticket system
You already guessed it right as a startup there is just a little resource problem on the support site. I usually try to respond to you on the same day. response times can get longer when writing from different time zones.

Mechanical Problems
As I already told in the ticket system, the wobble is most likely from the z axis. If you could help me out with some pictures I gladly help with that.

Hi Roman, thanks for responding here, as well as on the ticket system:), it's good to know that someone from Sintratec is looking in on us now and again.

Hi Roman,
nice to see you. and the quick answer at my ticket :-)))))
I hope that every one saw my statements in a constructive positiv view. My englich is not so good than my german :-) Talking with Sintratec is very helpful for me. And of course Sintratec tries to help :-) I hope i will not scare potencial customer to by a KIT. But sometimes a good community can help each other and someone shares the expirence other have made before (e.g. lamo cables). And Sintratec has not to solves probleme times and times again :-)

Nicely said, rudschul - a strong community can go a long way to help alleviate problems and frustrations by owners helping one another. The supplier (Sintratec) can also get valuable feedback from such a community but only if they too have a presence there. That's why it is good to see Roman responding on this forum. I think Sintratec would be advised to make this their goto forum before threads for Sintratec start on other forums. Alternatively start their own user group forum. There is no doubt that being able to chat with other users can sometimes be more valuable than just reporting to the supplier. Quite often a user will have a different perspective on the build and/or operation than the developers simply because the developers know exactly what they are doing after so many iterations that they don't necessarily see some of the pitfalls.

Having said that, I have found the build very straightforward and enjoyable. But for the problem with the galvo driver and switch, I would have been printing by now. Not sure how rigorous the testing is for the galvo drivers but the odd dud is bound to get through.

Keep up the good work Sintratec, you may be on a winner.

Well, it's taken five days but my replacement parts are finally on their way. Can't wait to get this thing fired up!! I have got quite a few things lined up to print as test pieces and a fair few friends have been quizzing me about it with a view to having bits printed for their model aircraft. Looks like I may be busy:D

Replacement driver and switch arrived today so I was pretty keen to get them fitted. Had to earn some brownie points first though before I could play:(. I first checked the driver was working by rigging it up without mounting it to the chassis. Yay, it was working and the Y axis galvo was doing its thing:D However, there was a bit of a problem with the new driver - the mounting holes were threaded 4mm not drilled as clearance as the original ones were but as the bolts are captive, between the two layers of aluminium and insulation, there was no way of getting the driver attached. It was clear they had to be drilled out 4mm. This I did, being very careful not to get any swarf into the electronics. That done, the driver and switch were positioned and fitted.

Next the printer was fired up and I could finally do the calibration. The galvos needed a lot of adjustment to get the pattern right but I got there in the end. Probably have to wait till tomorrow to get some powder in and a test print done.

It's not clear from the instructions but I am assuming just a small ammount of powder can be used without having to fill the powder chamber? Can anyone confirm?

It makes sense that you would place the amount of powder in the feed chamber that corresponds to the z-height of the object to print plus a bit more as a buffer. The printer should cease to load the build chamber when the print data end is reached. Any excess powder that is placed in the feed chamber will be subject to heating, reducing its value. I have not examined the software for this aspect, but if it is not of this nature, it is unquestionably wasteful.

Thanks fred, you are right that it does not make sense to fill the chamber if only making tests of small items. If I don't get a definitive answer from Sintratec, I will try with just a small amount.

You won't believe it but my new switch has just failed in exactly the same way as the last one did!!!!! After just three switch ons it is now permanently on. Not sure why this should happen unless the contacts are not rated for 240v

it's encouraging to see that you are getting support from Sintratec. They were quite helpful to me when I needed to clear the mechanical problems. I have to get moving one of these days and put my kit together again.

yes, Sintratec try to help where they can do.
@fred_dot_u: You will not need to fill the chamber completly. For calibration i think about 3 cm powder will be enough. At the beginning you will have to calibrate your temperature. If you have a lot of warping mostly your print will go autamaticly into trash. :-)
Keep aware the the glass is clean and is not between your IR sensor. If this happens your temperature will not be correct.

Quote:

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Originally Posted by Mike Francies

Replacement driver and switch arrived today so I was pretty keen to get them fitted. Had to earn some brownie points first though before I could play:(. I first checked the driver was working by rigging it up without mounting it to the chassis. Yay, it was working and the Y axis galvo was doing its thing:D However, there was a bit of a problem with the new driver - the mounting holes were threaded 4mm not drilled as clearance as the original ones were but as the bolts are captive, between the two layers of aluminium and insulation, there was no way of getting the driver attached. It was clear they had to be drilled out 4mm. This I did, being very careful not to get any swarf into the electronics. That done, the driver and switch were positioned and fitted.

Next the printer was fired up and I could finally do the calibration. The galvos needed a lot of adjustment to get the pattern right but I got there in the end. Probably have to wait till tomorrow to get some powder in and a test print done.

It's not clear from the instructions but I am assuming just a small ammount of powder can be used without having to fill the powder chamber? Can anyone confirm?

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Hi Mike its nice to hear that you are finally up and running!

You can calculate the powder like this:

You need 1 cm for every 100 layers (0.1mm layer high is standard) Also you will need additional 2 cm. 1 cm is for bed preparation and 1 cm is for cool-down. Also i suggest you put 5 mm to 1 cm more just to be sure.
So for the calibration print (5 mm) you will end up with about 3 cm space you need in the build chamber

For the feeding chamber this is a different story. you have to keep in mind that the density of the powder chances when sintering. From about 0.5 kg per liter to about 0.9 to 1 kg per liter (depending on the sintering strength). This means that you actually have to apply more powder to compensate. This means the feeding chamber will move about +25% the distance of the building chamber.

If you apply that knowledge to the calibration part you end up with 37.5 mm.

have fun printing :) if there are any more questions feel free to ask.

Thanks for the reply Roman. Below is a copy of a ticket I have just sent regarding my test prints.

Printer is now operational and I have been attempting the test print. First print was not good enough to measure in Z as the first few layers were deposited in the waste powder bin having been wiped out by the blade. It was good enough to measure in X and Y and these were way out, measuring just 34mm x 35mm. I unbolted the top and adjusted the galvo drivers by quite a lot and did a re-print. This time the print went fine with no layers lost. However, the X and Y were still a long way off at 36mm and 38mm - too much for the computed scaling. I have now altered the galvo drivers again and the test pattern is now overlapping the print chamber. Is this okay? Another test print planned for tomorrow. The quality of the print is disappointing with the bottom surface being convex and the top surface being very concave. Again, I cannot check the Z scaling because the surfaces are not flat. What is causing this? The surface seems very molten as the laser fills in the surface. Should I speed up the laser, widen the hatching or raise the surface temperature?

Maybe other could chime in with their thoughts too.

What is the color of the powder before the laser get active?
the convex bottom problem is a sign of warping and you have to change your temperature setting and to check that the IR sensor is working right.
Warping happens while part of the matierial fall under a spezic material temperatur and the material shinks at different point of the print. I hope you understand what try to say. My english is not so good.

What is your chamber temperature? (i take heat up 149,5 Printing 150) What is your surface temperatur? (166 / 170,5) What was your heat up time?

Hi Rudschul, colour of the powder is difficult to ascertain but it doesn't seem to discolour at all. I appreciate what you are saying about the warping and the difference in temperatures but I am using the default settings that Sintratec have set though I do realise these are only starting values. Heating up takes one hour forty five minutes and the chamber temperature is 140C and the surface temperature is 150C. When printing the surface temperature rises to 170C.

When sintering, the powder really does appear to melt and become molten rather than just fusing together. To me it suggests the laser needs speeding up but as I am at the very early stages of playing with this technology, I am open to suggestions.

140 C for the chamber is definitive to less. The shrinking of plastic happen at a specific temperature. The chamber temperature has to be highter than this temperature. With every layer you cool down your print. If you cool down to much shinking will happen and than your print is bad or destroyed. Roman told me that he uses alway 150C chamber temperature. Which printing speed do you use? I use 550,0 the default value.

Interesting - Roman has just responded to a ticket I sent about the issue and he says the chamber temperature does not matter too much.

The first prints were done at the default values with the laser set at 550 mm/sec. With the melting that seems to be happening, I am now trying the laser at 600mm/sec and I have also change the hatching from 50 micron to 75 micron. I know I should not change more than one value at a time but with a print taking so long it will take forever getting things right. I still don't know how close my X, Y and Z values are going to be after the latest adjustment of the galvo drivers and I cannot adjust Z until I get a flat print!

Now I am really frustrated. Two more aborted prints today:(. This time I loaded the print chamber with four of the test pieces, in a similar pattern to that shown in Roman's photo below. All four curled up at the edges and were dragged into the overflow bin with some of the molten Nylon sticking to the blade. This happened using the default values of; surface at 170C and chamber at 140C. For the second print I upped the surface to 175C and the chamber to 150C. This time was slightly better in that only three were wiped out - not much consolation!

However, there may have been a slight clue in the second print as the 'cake' surrounding the prints was much more solid than in previous attempts. In the first few prints there was very little 'cake' and the prints were surrounded by loose powder. In the last attempt, at 175C surface and 150C chamber, nearly all the powder in the print chamber was loosely holding together. So, just how solid should the 'cake' be and does this point to my surface temperature still being too low?

This is an extract that accompanied the photo from Roman's response to my ticket:
Also check the following things:
-the Laser glass may not cover the IR sensor
- the tube of the IR sensor may not touch the sheet metal beyond it
- The frontal light shade has to be adjusted correctly. the shade of has to be aligned exactly to the backside.

The last point is the one that is confusing me. I don't see much of a shadow on my powder or in the photo. If the frontal shade needs adjusting does it mean a complete disassembly of the hood? Not looking forward to that!!

Attachment 9833

i think the most importent thing is that you have an object that you could measure. Try to get first a nearly good print and than try to adjust the x,y,z. With the grid have an orientation. Try the folowing values:
heat up: chamber 149,5 surfarge 166
printing: chamber 150 surfage 170,5
speed 550

These values are not perfect but a good starting point.

yes this is important:

The frontal light shade has to be adjusted correctly. the shade of has to be aligned exactly to the backside.

You remember the L-Peaces near the lamps. The L-Peace of the front lamp makes the shadow. You can loosen the screw and move the L-peace