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Cherry Pi III Is Available

Posted by AndyCart 
Re: Cherry Pi III Is Available
March 16, 2015 03:32PM
Looking good there Matt! thumbs up
Re: Cherry Pi III Is Available
March 16, 2015 03:51PM
Thanks Doug, but like I said without this forum and your guys helping out it would be an expensive paper weight smiling smiley
Re: Cherry Pi III Is Available
March 16, 2015 06:32PM
Love the colour Matt. I'm curious as to why you went with an Airtripper extruder. I tried one once as it was so compact but decided mine needed a geared stepper to drive it properly and they were quite expensive so I went back to a Greg's Wade. If you have success I'd love to hear as I love the design.
Re: Cherry Pi III Is Available
March 16, 2015 06:52PM
Hi Andy,

I did a bit of reading around and supposedly you can get away with feeding more plastic types with a direct drive extruder. I know the down side is you need a bigger stepper motor (40N.cm torque+ ) to push the plastic but I thought I would give it ago. I purchased a high torque stepper motor for the job. Just looking for instructions to calibrate it now as 10mm extrudes about 46mm currently. I might be moving to the Greg's Wade if all goes wrong, I'll keep the forum unto date with my failures, sorry success with it smiling smiley
Re: Cherry Pi III Is Available
March 16, 2015 06:55PM
Day 15

I've finished the electrical installation other than the hot bed and a calibration cable. I'll get that done tomorrow lunchtime, athough if the weather is good, I may grab the RC gear and go flying.



The filament is on order and should arrive in the next couple of days and I may order a right angled USB connector as the straight one is putting a lot of strain on the socket where it's jambed against the frame. Either way it should see some power before the week is out. I just need to read and re-read the calibration guide.

Andy, what settings should I use in Cura for the print volume and such?

Edited 1 time(s). Last edit at 03/16/2015 06:58PM by gowen.
Re: Cherry Pi III Is Available
March 16, 2015 08:32PM

New head is doing nice prints but still getting slight jumps does anybody have any suggestions on what it could be.
On that print I was doing 0.1mmlayer,0.8mm shell thickness,0.6 bottom/top thickness,0 infill,195c temp,100% flow
retraction 35mm,4.5mm distance,initial layer 0.3,travel speed 80,bottom layer speed 20mm/s,bottom layer 20mm/s,all others 40mm/s
Re: Cherry Pi III Is Available
March 16, 2015 08:43PM
Quote
mrorange26

New head is doing nice prints but still getting slight jumps does anybody have any suggestions on what it could be.
On that print I was doing 0.1mmlayer,0.8mm shell thickness,0.6 bottom/top thickness,0 infill,195c temp,100% flow
retraction 35mm,4.5mm distance,initial layer 0.3,travel speed 80,bottom layer speed 20mm/s,bottom layer 20mm/s,all others 40mm/s

Wow man, that's looking great. Can't even see layers for the most part...
Re: Cherry Pi III Is Available
March 16, 2015 08:44PM
Yeah looked good but still getting the jumps in the upper part of the print.
Re: Cherry Pi III Is Available
March 17, 2015 04:18AM
Quote
AndyCart
Love the colour Matt. I'm curious as to why you went with an Airtripper extruder. I tried one once as it was so compact but decided mine needed a geared stepper to drive it properly and they were quite expensive so I went back to a Greg's Wade. If you have success I'd love to hear as I love the design.

Guy's I went with a Mini Mendel extruder as supplied by RepRapPro which is a very compact geared extruder and the STL's are available for it.



I know it cost me a bit of cash but it did come with a motor so it wasn't to bad. The red bracket is my own design and I modified the extruder body by drilling out the feed end to 9mm and fitting a Bowden connector 4mm bore 1/8 bspp thread I also drilled the connector out to 4 mm at the rear so that the PTFE tube would fit all the way thru.

to do it yourself would need 4 plastic parts plus the bracket main thing is that the body/gears need to be printed quite finely.

If anyone wants the Red bracket in the print then I will upload the STL for it.

Doug
Re: Cherry Pi III Is Available
March 17, 2015 05:29AM
I altered the DEFAULT_AXIS_STEPS_PER_UNIT for the extruder , I now get the right amount of material going through. I also connected the Bowden tube up the hot end and pushed some plastic through the nozzle. I had the temp set to 185 for pla and it pushed the plastic through using the extruder without any issues. Obviously this will be a bit different once there is back pressure but so far so good.

Matt
Re: Cherry Pi III Is Available
March 17, 2015 10:13AM
Can anyone give me a clue where to buy the 16x5x4 flanged bearings, preferably from a UK supplier?

I've tried all the usual suspects, without success - can you supply a set, Andy?

Edited 1 time(s). Last edit at 03/17/2015 10:28AM by David J.
Re: Cherry Pi III Is Available
March 17, 2015 10:35AM
Quote
David J
Can anyone give me a clue where to buy the 16x5x4 flanged bearings, preferably from a UK supplier?

I've tried all the usual suspects, without success - can you supply a set, Andy?

Shouldn't be to hard to find or you could do what I have done and use toothed pulley's.

You could always use F625zz bearings which are slightly wider and commonly used in model cars (Traxas/Tamiya).

Doug
Re: Cherry Pi III Is Available
March 17, 2015 11:22AM
I have found some that are 5mm id, 13mm od and 4mm wide - F695 - I guess those would be OK as the toothed pulleys are approx 12mm in diameter, so a reasonable match.

Edited 1 time(s). Last edit at 03/17/2015 11:32AM by David J.
Re: Cherry Pi III Is Available
March 17, 2015 11:44AM
Quote
David J
I have found some that are 5mm id, 13mm od and 4mm wide - F695 - I guess those would be OK as the toothed pulleys are approx 12mm in diameter, so a reasonable match.

They are the ones I use now too. I buy them from China.
Re: Cherry Pi III Is Available
March 17, 2015 11:46AM
Good news - thanks Doug & Andy
Re: Cherry Pi III Is Available
March 17, 2015 11:47AM
Quote
mrorange26
Yeah looked good but still getting the jumps in the upper part of the print.

Now that you have your carriages sorted, and assuming it's not a slicing issue, there are only a couple of possibilities, either your belts are too slack or your stepper drivers aren't supplying quite enough current. Both are easy to investigate and fix luckily. One other thing to check is that the pulleys on your stepper motors are tight. There are two grub screws on each one. Maybe give them a nip.

Edited 1 time(s). Last edit at 03/17/2015 11:49AM by AndyCart.
Re: Cherry Pi III Is Available
March 17, 2015 01:57PM
I was wondering how tight the belts should be.
Re: Cherry Pi III Is Available
March 17, 2015 03:00PM
Quote
mrorange26
I was wondering how tight the belts should be.

They don't need to sound a musical note when you pluck them but they should be tight enough that it takes some force to make one touch the other in the middle. The stepper motor mounts have slots in them so if you loosen the four screws and press down on the top of the motor whilst you nip them up again that should be fine. If they are already bottomed out on the slots then loosen the screws and re make the connection on the rod carrier but take a bit more belt round the loop. Then tighten via the motor slots as above. The object is to remove play from the mechanism. Don't forget to check the pulleys for a secure fit on the motor shafts too.
Re: Cherry Pi III Is Available
March 17, 2015 03:02PM
Ok mine have quite abit of play in them.Is there any easy way to get the the screws on the motor to loosen them.
Re: Cherry Pi III Is Available
March 17, 2015 03:05PM
Quote
mrorange26
Ok mine have quite abit of play in them.Is there any easy way to get the the screws on the motor to loosen them.

You need a 3mm ball end Allen driver (or a long Allen key). You can just insert it through the access holes on the outside of the stepper base. They are directly in line with the stepper mounting screws.
Re: Cherry Pi III Is Available
March 17, 2015 03:06PM
Lol sorry didn't even see the holes until you just said.
Re: Cherry Pi III Is Available
March 17, 2015 05:17PM
Hi andy I have tightened belts and check grub screws on motors there all fine.Still getting jumps,What can I do next.
Re: Cherry Pi III Is Available
March 17, 2015 07:08PM
Quote
mrorange26
Hi andy I have tightened belts and check grub screws on motors there all fine.Still getting jumps,What can I do next.

Have you checked/adjusted the stepper driver current with the small potentiometers on the A4988 boards for X Y and Z?
Re: Cherry Pi III Is Available
March 17, 2015 07:11PM
No I haven't yet.But I have just check my rods and some of the balls weren't pushed right on so made them different lengths.I have checked them all now and recalibrated again,Just started a new print and its looking good so far,Could this cause problems.
Re: Cherry Pi III Is Available
March 17, 2015 07:13PM
Quote
mrorange26
No I haven't yet.But I have just check my rods and some of the balls weren't pushed right on so made them different lengths.I have checked them all now and recalibrated again,Just started a new print and its looking good so far,Could this cause problems.

Definitely
Re: Cherry Pi III Is Available
March 17, 2015 07:15PM
They are all will like 3.5.3.9,3.8 where as 1 was 5.1 before.
Re: Cherry Pi III Is Available
March 17, 2015 07:25PM
Sorry bad English,they are all about 3. something now
Re: Cherry Pi III Is Available
March 17, 2015 07:30PM
Quote
mrorange26
Sorry bad English,they are all about 3. something now

Are you talking about the limit switch offsets?
Re: Cherry Pi III Is Available
March 17, 2015 07:32PM
On X,Y,Z when you bring the print head down with a piece of paper just under it on the bed.
X (Endstop Adj):
Y (Endstop Adj):
Z (Endstop Adj):
Re: Cherry Pi III Is Available
March 17, 2015 07:37PM
Stopped print halfway through its abit better but still a few lines how do I adjust stepper motors.
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