Ebay SINTRON Kossel Mini full kit

Samlittlewood, that sounds like a really good way to get your frame straight and true. I wish I'd done that the first time, instead of having to do it again when I realised that everything was slightly off.

I'm now doing it again on a friend's XL Kossel with metal corners. Believe it or not but I can really see the flex in this design, even with metal corners. I'm going to put in some turnbuckles to pull it all into line. "Calibrated" nudges as I tighten some custom diagonal braces just isn't accurate enough.

I have finished making my led strip lights for my printer, and they have all turned out quite accurate considering my printer is no where near set up right.

It is on www.thingiverse.com

You can see some pics of them here

The way that these little strips have turned out is making me think I might have a chance of printing the plastic parts for my new RepRap Prusa i3

Apparently Cartesian printers are easier to set up than Delta's, so if I can print the plastics and get them something like, then I can put them on the i3 and print them again, and better, on the i3.

Quote
Electric ant
The way that these little strips have turned out is making me think I might have a chance of printing the plastic parts for my new RepRap Prusa i3

Apparently Cartesian printers are easier to set up than Delta's, so if I can print the plastics and get them something like, then I can put them on the i3 and print them again, and better, on the i3.

I have reprinted almost all plastic of my i3 on this delta and printed some delta parts on i3, they cross-polinate nicely. All in all I wouldn't say i3 is more precise than delta, but neither is perfect, so it might of course be me

Quote
Electric ant
I have finished making my led strip lights for my printer, and they have all turned out quite accurate considering my printer is no where near set up right.

It is on www.thingiverse.com

You can see some pics of them here

The way that these little strips have turned out is making me think I might have a chance of printing the plastic parts for my new RepRap Prusa i3

Apparently Cartesian printers are easier to set up than Delta's, so if I can print the plastics and get them something like, then I can put them on the i3 and print them again, and better, on the i3.

I was looking for an LED option too. But opted for battery operated worklight hanging over the kossel. I have too many wires and outlet plugs already. I have decided to have a dedicated PSU for the fans and that takes up another outelt.

Well slowly again, the Sintron Kossel is going to get replaced part by part. Today, I was printing and noticed oozing from the nozzle. I checked and the heatbreak tube and nozzle were loose. So I turned them with a wrench. Then under the pressure of just the heat and oozing PETG, the nozzle kept popping out. Bad news. I think I warped or ruined the aluminum heatblock. So now I have 2 choices. Buy a replacement heatblock and hope that it fits my nozzle and heatbreak throat tube or 2 just buy a whole new hotened.

Any ideas?

Quote
DRTak
Well slowly again, the Sintron Kossel is going to get replaced part by part. Today, I was printing and noticed oozing from the nozzle. I checked and the heatbreak tube and nozzle were loose. So I turned them with a wrench. Then under the pressure of just the heat and oozing PETG, the nozzle kept popping out. Bad news. I think I warped or ruined the aluminum heatblock. So now I have 2 choices. Buy a replacement heatblock and hope that it fits my nozzle and heatbreak throat tube or 2 just buy a whole new hotened.

Any ideas?

I would go for e3d (which I did — I could've given you the original sintron hotend for parts).

I'm ready to start calibrating for size now and I know that the delta_diagonal_rod_length will affect the size of the print.
2 questions,
1, Why should the length be changed if this is the length my rods are at, and
2, What size change would be affective, e.g. if I need to lose 0.2mm from a 20mm print, would I change the rod length by 10ths or whole numbers ?

On to quality, can anyone tell me why this is happening to my prints, I think maybe the plastic isn't cooling down fast enough when it leaves the hot head, so the line of fresh warm plastic falls to 1 side then the next layer has nothing to stick to.
But I'm probably wrong, after all I'm still a 3D printer noob.

Just when you sort 1 thing out, something else needs attention. But that's the fun of buying a kit.
I will get there, eventually, with help from you guys, I hope.

Thanks,

Ant

Ant:

Measure your rods carefully from centre of ball to centre of ball, plug that number in, and then don't touch it ever again. The advice to change diagonal rod length to scale your print size is wrong. It causes geometry problems elsewhere.

For calibration I've come up with a print that is not extrusion dependant - you can identify scale even if your extrusion rate is way off.

Most likely is that your steps per mm is wrong. This needs to be calibrated for your particular belts. GT2 belt is not exactly 2mm. You need to firstly get your frame 100%square, then measure carefully how far the carriages move, and adjust your steps per mm for each acis until the carriages move perfectly. Once this is done, and you've redone your endstops and delta radius numbers, you should get perfectly sized prints.

Quote
nebbian
Most likely is that your steps per mm is wrong. This needs to be calibrated for your particular belts. GT2 belt is not exactly 2mm. You need to firstly get your frame 100%square, then measure carefully how far the carriages move, and adjust your steps per mm for each acis until the carriages move perfectly. Once this is done, and you've redone your endstops and delta radius numbers, you should get perfectly sized prints.

This actually sounds easier than changing the diagonal rod length. We shall see.

First thing is, where is the steps_per_mm located in the Marlin firmware ? All I can find in the config file is #define DEFAULT_AXIS_STEPS_PER_UNIT {80, 80, 80, 95}
Is it even in the config file ?

I have just designed a little sizing calibration item for me to print and measure when I am ready.

I have already used the endstop offsets, so that's not a problem, but....
Second thing, what is meant by the delta_radius, is this the size if the print bed or the size if the print area or, is it something else ?
I am still using the Sintron circular MK3 bed provided in the kit, so would this be 220mm for print bed or 170mm for print area ?

Like I have said before, this is my first experience with a 3D printer and you guys have been an amazing help. I know I wouldn't have got this far without this forum page, so close to getting my first totally accurate print.
I'm not too bothered about the quality yet as long as I can get the sizes right. Temps and extrusion rate are next on my list, after this sizing calibration mission.

Thanks again guys.
And keep the good advice flowing.

Ant

Steps per mm is steps per unit. You need to modify those 80 numbers. To do this, get a set of calipers, and set them up so that you can measure 100mm of travel on a carriage. Home your printer, and gradually move the head down until the carriage is moving your caliper jaws. Zero your calipers. Now move down in steps of 10mm, watching the number after the decimal point. Chances are that this number will slowly decrease. This means your steps per unit is wrong. Adjust those 80 numbers until you get perfect 100mm movement. You need to measure each carriage, as the belts are different.

Delta radius is what is calculated by the smooth rod offset, effector offset, and carriage offset. If you're using eeprom then you adjust it directly, if using the firmware and adjusting configuration.h then you adjust smooth rod offset. Adjusting this number gives you a flat printing surface.

Try the attached file, when slicing rotate it around so that it looks like a Y. After printing it, use your calipers and measure from the outside, to the inside of the outermost block, then keep the jaw on the outside block but then measure to the inside of the next block and the next, etc. Eg: 10mm, 29.9mm, 49.8mm, 69.7mm, 89.6mm. This shows that you're printing about 0.5% undersized if you get those numbers.

This method takes care of extrusion errors, and shows you any scaling issues you might have.

Good luck.

A valuable and logical explanation. Everyone can benefit from this. Thank you nebbian.

I also switched to a e3d v6 hotend. You get a bonus of 2cm extra build height with the v6, compared to the sintron hotend.

Edited 1 time(s). Last edit at 03/19/2016 06:06PM by CrisCG.

@nebbian
I tried to print your config object but its bigger than my print area.
When the head came in front of the Y tower, during the outer ring print, one of the belts started slipping (not sure which 1) and the head moved away from the Y tower in a straight line towards what would be the back right corner.
The head then moved left and round in front of the Z tower to the back left corner, now the head is about 1.5 to 2mm away from the bed.
Next another belt starts to slip and the head moves in a straight line towards the X tower, now the head is about 3 to 4mm above the bed.
I think my printer is set for a max print area of 170mm so it won't print the outer ring.

I don't understand how it can reach the front and back but not the sides. I will have to see if I can change my print area to 180 and try again.
According to my calibration print, my printer is over on the X axis by 0.15mm to 0.18mm-ish per 10mm, my Y axis is almost bang on and Z is over by about 0.8mm per 10mm.

Just as an experiment I changed the X steps to 78 in pronterface with M92. It lifted the head about 2mm.

I'm going to try to set my steps_per_mm tomorrow, and I may put a screw in the tops of the carriages to set the endstops with.
I don't like messing with offset numbers, sometimes you just can't get it accurate enough. Or is that just me........

For better precision, switch to repetier firmware with repetier host. The endstop offsets are set in steps, and you can move the carriage with 0.01mm.

@CrisCG
I have tried repetier when I first got my printer, I find marlin easier to understand. I can't even find the Z max height in repetier.
I want to follow a vid on calibrating with M666 and M665, in the vid the guy has the Z axis going in to the minus numbers (as though the head is lower than the bed) but in marlin I can't go lower than zero. The S1 command does not override the zero endstop position for me.
My Z axis endstop does not change with M666.
Also, M500 does not save my settings to eeprom. Every time I connect my printer I have to M666 Y-0.5 to set my Y axis. I think a screw in the top of the carriage will work better. This way I can leave all my endstop offsets at zero.

On the subject of size, all my prints are coming out different sizes. If I print the same thing on 2 separate prints, they will not be exactly the same size. There can be as much as 0.5mm to 1mm difference on the X axis and -0.3mm to 0.5mm on the Y. My Z is quite consistent and accurate.

I have got an idea for a bracket to get the uprights perfectly straight. I have got ALL the parts for an i3 coming next week, some parts I have already. My plan is to build the i3, calibrate it, do some test prints and hopefully not have as much trouble as I've had with the Delta.
If all goes according to plan and the i3 prints are accurate, I can design the bracket for the Delta, print 3 of them on the i3, install them on the delta, and try again.
My delta frame is not 100% square although all the corners are 60°. I would say my frame is 99% square, but that extra 1% could be the difference between accurate and wrong sized prints.

If I decide to go ahead with the brackets, I may also try the suggestions by samlittlewood on the previous page. My last partial strip down and rebuild made it better, maybe another will fix it for good.

Quote
CrisCG
A valuable and logical explanation. Everyone can benefit from this. Thank you nebbian.

I also switched to a e3d v6 hotend. You get a bonus of 2cm extra build height with the v6, compared to the sintron hotend.

I thought the Sintron hotend was an e3d V6 clone? Is it e3d v6 lite?

Quote
DRTak

Quote
CrisCG
A valuable and logical explanation. Everyone can benefit from this. Thank you nebbian.

I also switched to a e3d v6 hotend. You get a bonus of 2cm extra build height with the v6, compared to the sintron hotend.

I thought the Sintron hotend was an e3d V6 clone? Is it e3d v6 lite?

Neither. It's somewhat e3d-like.

has anyone got a nice solution to mount the sintron mk3 heatbed please ?

There are 2 or 3 mounts on thingiverse, you can try those. If you've bought the kit, then you have a long screw, washer and springs for the bed. There are some pictures a few pages back.

My bed is mounted using 3x M3 nuts, the 3 small springs, 3x T-nuts and 3 of the supplied screws.
I have enough spring to cope with a small head crash and the M3 nut makes it easier to adjust than the square nut.



You could put a washer between the spring and the bed but I don't think it's needed.

I've lost count of how many different ways I tried to mount my bed, either permanent fit or removable, and this is by far the best way for mine. But there probably are better ways out there.
It has enough spring for that unexpected head crash and plenty of thread left for adjustments.

Hope this is of some use to you.

Ant

Quote
Electric ant
My bed is mounted using 3x M3 nuts, the 3 small springs, 3x T-nuts and 3 of the supplied screws.
I have enough spring to cope with a small head crash and the M3 nut makes it easier to adjust than the square nut.

[attachment 75015 MK3SintronBed.jpg]

You could put a washer between the spring and the bed but I don't think it's needed.

I've lost count of how many different ways I tried to mount my bed, either permanent fit or removable, and this is by far the best way for mine. But there probably are better ways out there.
It has enough spring for that unexpected head crash and plenty of thread left for adjustments.

Hope this is of some use to you.

Ant

Hey thanks for that. I was using shorter screws and no nut. But now the nut in between is just what I was looking for. I will do that and then I will have more travel with the bed for adjustments.

Quote
Electric ant
My bed is mounted using 3x M3 nuts, the 3 small springs, 3x T-nuts and 3 of the supplied screws.
I have enough spring to cope with a small head crash and the M3 nut makes it easier to adjust than the square nut.

[attachment 75015 MK3SintronBed.jpg]

You could put a washer between the spring and the bed but I don't think it's needed.

I've lost count of how many different ways I tried to mount my bed, either permanent fit or removable, and this is by far the best way for mine. But there probably are better ways out there.
It has enough spring for that unexpected head crash and plenty of thread left for adjustments.

Hope this is of some use to you.

Ant

thank you Electric ant ill try that, do you insulate the bottom on your heatbed?

i bought a complete frame and heatbed hardly used that the guy was foxed by the large metal rod ends, and another sintron kossel in used bits that also beat the owner and he gave up with it , im building up a good one with the aid of the tips in this thread (which i thank you all for ) and my trusty 3dr delta , mine will be duet 0.6 powered does anyone have a working dc42's firmware that i could have a copy of please? that would save a bit of time for me

heres mine so far

Quote
forest
i bought a complete frame and heatbed hardly used that the guy was foxed by the large metal rod ends, and another sintron kossel in used bits that also beat the owner and he gave up with it , im building up a good one with the aid of the tips in this thread (which i thank you all for ) and my trusty 3dr delta , mine will be duet 0.6 powered does anyone have a working dc42's firmware that i could have a copy of please? that would save a bit of time for me

firmware binaries are available in the repository, you just update it and that's it. As for configuration you can also take the default, go through it and change the values you'd have to change for your particular build anyway.

Happy that my bed fittings are good enough for you guys.

@forest

Insulation.....
I just got a piece of corrugated card, cut to shape to fit the under the heat bed and rest on top of the stepper motors and covered it with aluminium foil tape.
Make sure you put the tape side facing the heat bed, I also covered the solder points with electrical tape.

I hope you have better luck with yours than I had with mine, it took me ages to get mine working to a satisfactory level. Now that it's printing pretty good, there's not that much more I can do with mine. Some more fine tuning and it's done.
Then, on to building my i3.
Only waiting for RAMPS board and drivers, pulley's and belt, plastic parts, couplers and heat bed now.

Quote
nebbian
measure carefully how far the carriages move, and adjust your steps per mm for each acis until the carriages move perfectly

I have done the Z axis and got it to 10.02mm carriage movement for every 10mm step on pronterface.

How do I do the X and Y axis ? these don't move like the Z axis. If you move the y carriage for example, the other 2 move as well.
How do I check if x and y are correct when the carriages don't move by the amount shown in pronterface.
Do I put a mark on the print bed and measure how far the head moves over the bed with a 10mm click ?

I think this is almost the last thing I need to do now before I get that (near) perfect print.


Ant

Quote
Electric ant

Quote
nebbian
measure carefully how far the carriages move, and adjust your steps per mm for each acis until the carriages move perfectly

I have done the Z axis and got it to 10.02mm carriage movement for every 10mm step on pronterface.

How do I do the X and Y axis ? these don't move like the Z axis. If you move the y carriage for example, the other 2 move as well.
How do I check if x and y are correct when the carriages don't move by the amount shown in pronterface.
Do I put a mark on the print bed and measure how far the head moves over the bed with a 10mm click ?

I think this is almost the last thing I need to do now before I get that (near) perfect print.


Ant

My guess is that you do it exactly like Z. That is move 10mm along Z axis on pronterface.

On a delta, the X Y and Z steps/mm should all be the same, unless you have any reason to suspect that your belts have different tooth pitches. Adjust the steps/mm of all three to get the correct height when you print a tall object. If you are using good belts, it should be extremely close to the theoretical value.

Getting the printed X and Y sizes correct is all about good machine geometry and having the correct diagonal rod length configured in the firmware.

---

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].

Quote
dc42
On a delta, the X Y and Z steps/mm should all be the same, unless you have any reason to suspect that your belts have different tooth pitches. Adjust the steps/mm of all three to get the correct height when you print a tall object. If you are using good belts, it should be extremely close to the theoretical value.

Getting the printed X and Y sizes correct is all about good machine geometry and having the correct diagonal rod length configured in the firmware.

On my Sintron kit, I had to adjust my steps per mm from 80 (calculated) to around 80.2 after lots of very careful measuring. Strangely enough all three belts were different. You only have to do this if you are concerned about parts printing roughly 0.5% small. I was concerned about this, so adjusted it.

As DC42 says, machine geometry and correct diagonal rod length has more of an effect than the steps per mm value -- but the steps per mm DOES have an effect, and is worth doing if you're interested in getting your prints spot on. Mine are within 0.1% in all dimensions now. This was after literally weeks of pulling apart, measuring, putting back together, tweaking, adjusting, measuring, hypothesising, printing new parts, and the list goes on.

My list in order of importance for getting accurate parts:
* Calibrate extruder
* Get your towers parallel
* Get your towers square to each other and not twisted
* Get your bed square to your towers
* Put all diagonal rods on a jig to test that they are all exactly the same length
* Carefully measure the diagonal length of your jig, twice, two different ways, until you are absolutely certain of that value
* Carefully measure the width of mounting points for your diagonal rods, and adjust until all are exactly the same
* Verify that there is no effector tilt
* NOW test steps per mm of all towers and adjust until they are spot on

As you can see, the steps per mm is low down the list. It does have an effect though.

Well I decided to buy a Hexagon hotend. I wanted all metal with one single heat barrel tube. I disassembled the old hotend from the effector and tried to put the hexagon on it. But it wasnt fitting right. So I took a birds eye view and the Sintron red printed effector is warped. This would explain why I couldnt get accurate printed parts.

So that means my machine is down again. This time I will need to buy a Metal effector. Also need to figure out a way to mount dc42 IR sensor since the hexagon is shorter than the e3d v6 sintron clone.

My Sintron effector warped as well. I got a ABS effector now, with the e3d v6 hotend.

Edited 1 time(s). Last edit at 03/25/2016 03:11AM by CrisCG.

Quote
CrisCG
My Sintron effector warped as well. I got a ABS effector now, with the e3d v6 hotend.

CrisCG. Really yours warped too. How did you find out? Were you getting odd prints and you checked?

I have ABS moulded carriages which is fine because no real heat goes there. But Im afraid to buy, print, or have ABS printed/molded effector since I am going to experiment with exotic filaments. And they use high temps. I want to make sure that if a fan goes down, the effector wont warp again. So I am left with one solution. Metal.

From a cost point, this is the same price. I dont know why the nylon effector central hole has to be moveable? But I DID NOT get this one: [www.amazon.com]

The other high end one was this one. It has the electronic hookups prebuilt into the effector as well as an LED light. But cost too much and also made of nylon or glass fiber. [www.amazon.com]

There are some odd things about the Sintron machine that Im amazed no one has talked about. The machine at least mine is made with almost all M3 screws and nuts. The effector is M3. So if you google M3 metal effector very little comes up. The ones that do fit do not really fit. They have a 16mm central hole with a 13mm lip inside of the hole. Therefore the hotend cannot completely go through the effector. I have decided to buy one of these. But now there is no existing U mount groove plate to affix the hotend to the metal effector. NONE of the Kossel plates are 4.5mm in thickeness. So my solution was to cut the J head aluminum mounting plate that I had left over. It looks exactly like this: [www.amazon.com]

But again, this leaves me with no way to mount my IR sensor. I will have to find a solution for that.