Another Sintratec kit built

[Mike Francies]

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

[rudschul]

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 :-)

[fred_dot_u]

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.

[rudschul]

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.

[fred_dot_u]

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

s-l500.jpg

[Mike Francies]

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

[fred_dot_u]

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.

[Mike Francies]

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.

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.

[rudschul]

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.
L001_2.jpg
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.
PA102418.jpg
A good print:
good.jpg

[Mike Francies]

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