Build finished and almost printed something but...

Hi All,

ok I have a few questions and I think that my problem may well be down to mechanical issues. I finished my printer using the instructions last night and went through all the commissioning elements in the manual - The instructions were vague in parts but not so much that I couldn't correct any mistakes I made after doing it wrong...

1) The threaded balls on the effector assembly are painful in the extreme, I understand that the distance between the threaded ball needs to be the same (or v.near) to the distance on the carriage to get the arms parallel. I got to within 0.2 of a mm but the actual distances on the three arms were different - Is it the case that so long as the arms are parallel on each carriage there is no problem or do they need to be as identical as possible?

2) I've read that the actual arms are likely to break after some use and I want to prepare for that - does anyone have a link to howto make the carbon fibre replacements that I have seen mentioned in a few places? Also a source of raw materials or links for them would be good if this is something I need to learn/do myself.

3) The extruder drive! it's very difficult to get the extruder to accept filament I have the guide tube inserted but it doesn't seem to help, it comes free easily - did I not fit it properly perhaps? If I put a small kink in the end it does feed with some effort on my part to guide it manually. I can't help feel I've missed something here and this should be easier.

4) Extrusion test worked, I then stopped everything and went for my first print. I found that nothing was extruded although the head was moving properly. The extruder motor was clicking I think, so I decided to extract the filament and restart things. Extracting the filament was pretty difficult in the end but I dissembled and then cleaned out the tubes.The extracted filament seemed to have bulged at one end slightly I guess due to melting? So my question is what could stop the extrusion? Did the test I did block the hot end somehow? What are the best ways to clear this problem? links or suggestions gratefully received

Coupled with (4) are there general procedures for how to use the filament? should I retract it after printing? leave it in place? clean between every print etc? I am googling like mad myself but not always using the right terms to find what I need I suspect...

I don't have a Fisher but here is my advice:

1. It's ok to have different bearing spacings on the 3 pairs of arms, if each pair has the same spacing top and bottom.

3. With most extruder drives, feeding filament is easier if you use wire cutters to cut the end of the filament at a sharp angle before you insert it.

4. Is the hot end fan running and keeping the heatsink cool? If it is, then the bulge was probably caused by retracting filament too much while it was hot. Cool the hot end to about 100C to 120C before retracting all the filament, and retract the first 20mm slowly.

Some PLA filaments go brittle if you leave them in the machine overnight. Those need to be removed when you finish printing. Other filaments don't go brittle and can be left in the machine.

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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].

Thanks dc, I'll try these things out. I did retract while the head was hot as well so that may well be the issue there.

I've bumped the carbon arm build instructions back to the top of the forum if you look through the forum you should also find ideas others have for making jigs to help get them to the right length

[forums.reprap.org]

The ball spacing is not the most critical part of the fisher build, but the more accurately spaced they are then the more accurately your machine will function, I did make alternative carriage and effector parts that made it easier to get the ball spacing correct (mine are now within 0.05mm...or at least were the last time I rebuilt it), Here is a link to my easy adjust parts, however, be warned these are for the fisher beta, not the fisher 1, but it should be fairly easy to make similar changes to Fisher 1 parts to achieve the same results

[forums.reprap.org]

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RepRapPro Mendel 3 Tricolour
RepRapPro Fisher
-Carbon Arms
-Easy adjust Carriage+effector
-axis stiffness mods
HE3D -600 delta
-Duet 0.8.5
-PanelDue
-DC42 Height probe
-RobotDigg metal components
Simplyfy3D
RS Design Spark CAD

Hey Thanks for the links

I got the printer working now and it was mainly mechanical naivety on my part that stopped me from doing this sooner.

to anyone building this for the first time, make sure you have the right tools - it makes a huge difference and I think I would have stalled had I not had ball ended allen keys. For the rest I had a screwdriver and suitable hex bit, and a socket attachment for the nylock nuts - read the list of required tools!

in case others are reading this and have similar issues to mine (In no particular order):

1) I retracted the filament from the hot end during cooling and blocked up everything. As DC said above allow the hot end to cool before retracting and don't retract too fast. I have learned quite quickly that slower is better (at least to begin with I think). The blockage meant I had to disassemble the hot end to clear it out. I also played with the temperature too much and I think I melted the same strand of filament again and again in the hotend while intermittantly playing with the extruder drive....

2) The extruder drive was down to be not understanding it I think. I was trying to force the filament into the drive without understanding that the idler lever was actually stopping the filament from getting through the hobbed insert. Simply lifting the lever while inserting the filament initially got the thing working like a dream. I suspect that I should have seen this sooner but thats why I say naivety was my problem. I assumed it would just feed into the drive since the lever is quite out of the way inside the printer body.

3) While putting on the side panels one snapped around the hole for the top screw - it hasn't apparently affected the build but the acrylic is quite fragile.

4) The connections for the end-stops (microswitches) are loose and can come off. If motors suddenly stop working check that they are still in place (I will probably sort out some better way of connecting these I think since moving tubes and looms knock things off occasionally.

5) The arms - when the print head was on the extreme edges an arm was popping off. This is because an adjacent one was pushing against it. I had to reduce the width of the ball spacing to allow the head to move freely. Another reason why I am going to look at the head mods I think.

6) careful about positioning cable ties, they can impede the moving parts (carriage against end-stop cable tie for example) but also are pretty necessary or wiring will then be a problem.

7) lastly the wiring on my loom for the hotend was wrong, it was reversed in the plug and had I matched colours on the extruder side I may well have had issues electronically. However I followed the wiring diagram in the instructions and then plugged everything in and tested before noticing.

All in all, I am really pleased with the results so far but it has been a steep learning curve

Edited 1 time(s). Last edit at 12/31/2015 07:45AM by Caribou.

Quote
bgkdavis
I've bumped the carbon arm build instructions back to the top of the forum if you look through the forum you should also find ideas others have for making jigs to help get them to the right length

[forums.reprap.org]

The ball spacing is not the most critical part of the fisher build, but the more accurately spaced they are then the more accurately your machine will function, I did make alternative carriage and effector parts that made it easier to get the ball spacing correct (mine are now within 0.05mm...or at least were the last time I rebuilt it), Here is a link to my easy adjust parts, however, be warned these are for the fisher beta, not the fisher 1, but it should be fairly easy to make similar changes to Fisher 1 parts to achieve the same results

[forums.reprap.org]

I'll take a look at that, I think this and the extruder could be better - look at me running before i can crawl