Re: Folger Prusa i3 Kit from ebay March 19, 2015 12:45PM Registered: 9 years ago Posts: 14
Quote
Zavashier
IMPORTANT NOTE

I wondered why there were a noticeable difference between X and Z dimentions to my prints. Then I found where it comes from, and fixed it.

You definitely want to change the printed pulleys provided by Folger because they are ways too big. Some explanations : The Folger's printed pulleys have a contact diameter of 15.8mm, let's say 16mm. The pitch diameter of a 20 tooth GT2 pulley is (Pitch x Number of teeth) / Pi = (2*20)/Pi = 12,73mm. So they're definitely wrong. BUT, the pulley's pitch diameter differs of an idler pulley contact diameter. Because the tooth lay inside the pulley, and must have enough space on the idler pulley for the same belt pitch diameter. You need to remove the tooth eight plus the PLD of the pitch diameter to get the right diameter. So the GT2 belt's PLD is 0.254mm and the tooth eight is 0.75mm. You need to substact those two times for the diameter, so the formula is Pitch diameter - ((PLD+Tooth height)*2) = 12.73 - ((0.254+0.75)*2) = 10.72mm So you'd rather use the bearing alone, you're more closer ! You need to print a 10.72mm idler pulley if you've got a nozzle thin enough (0.3 or less) and/or buy a 694ZZ bearing mounted with M4 bolt and nut, and accept a 0.27mm error, which is tangently no big deal.

5mm of error on the diameter of the idler pulleys... Just a tiny gap !

Wait.. what?

Are you talking about the X & Y idler pulleys? (the only 'printed pulleys' included in the kit).. cuz.. the size of the idler pulley has no affect on speed/travel distance of the X or Y carriage.
 Re: Folger Prusa i3 Kit from ebay March 19, 2015 12:51PM Registered: 9 years ago Posts: 52
Hello everybody! I have been reading this thread for awhile now. Was extremely useful to me in deciding to purchase this printer kit. I cannot express how grateful I am to everyone that has contributed! The amount of information in this thread and how helpful everyone has been is truly amazing!

I placed my order March 8th. I am so excited and cannot wait for it to ship! I will post here when I receive it, I am really looking forward to being able to contribute to the community.

Dave
 Re: Folger Prusa i3 Kit from ebay March 19, 2015 02:53PM Registered: 9 years ago Posts: 1,011
Quote
TheLost
Wait.. what?

Are you talking about the X & Y idler pulleys? (the only 'printed pulleys' included in the kit).. cuz.. the size of the idler pulley has no affect on speed/travel distance of the X or Y carriage.
Of course it affects if the system is not parallel. As far the pulleys form a triangle with the bet attachment, the travel is not equal to the travel around the driving pulley. That was the problem on my printer. See attached picture. If you still desagree, I don't want to argue. Ask an engineer you trust.

Edited 1 time(s). Last edit at 03/19/2015 02:56PM by Zavashier.

Collective intelligence emerges when a group of people work together effectively. Prusa i3 Folger (A lot of the parts are wrong, boring !)
 Re: Folger Prusa i3 Kit from ebay March 19, 2015 04:19PM Registered: 9 years ago Posts: 14
Quote
Zavashier
Quote
TheLost
Wait.. what?

Are you talking about the X & Y idler pulleys? (the only 'printed pulleys' included in the kit).. cuz.. the size of the idler pulley has no affect on speed/travel distance of the X or Y carriage.
Of course it affects if the system is not parallel. As far the pulleys form a triangle with the bet attachment, the travel is not equal to the travel around the driving pulley. That was the problem on my printer. See attached picture. If you still desagree, I don't want to argue. Ask an engineer you trust.

Not arguing.. Just curious.. (i took physics and mechanical engineering in college).

How does the idler pulley size change the distance the belt travels? (answer.. it cant)

[www.prusaprinters.org]
(i don't see an input for idler pulley size)

For the record... I've ran the stock Folger pulleys (Y & X) since i got the kit and my prints are dead-on-accurate. I could put a 50mm pulley on my X Idler and as long as my firmware settings are accurate for my motor/belt/gear ratios it will have no affect.

Again... not arguing.. just want to make sure we are not speeding wrong information.

Edited 1 time(s). Last edit at 03/19/2015 04:20PM by TheLost.
 Re: Folger Prusa i3 Kit from ebay March 19, 2015 04:26PM Registered: 9 years ago Posts: 1,011
Fine. Try your 50mm pulley and get dead on accurate prints.

Collective intelligence emerges when a group of people work together effectively. Prusa i3 Folger (A lot of the parts are wrong, boring !)
 Re: Folger Prusa i3 Kit from ebay March 19, 2015 05:03PM Registered: 9 years ago Posts: 110
Quote
TheLost
Quote
Zavashier
Quote
TheLost
Wait.. what?

Are you talking about the X & Y idler pulleys? (the only 'printed pulleys' included in the kit).. cuz.. the size of the idler pulley has no affect on speed/travel distance of the X or Y carriage.
Of course it affects if the system is not parallel. As far the pulleys form a triangle with the bet attachment, the travel is not equal to the travel around the driving pulley. That was the problem on my printer. See attached picture. If you still desagree, I don't want to argue. Ask an engineer you trust.

Not arguing.. Just curious.. (i took physics and mechanical engineering in college).

How does the idler pulley size change the distance the belt travels? (answer.. it cant)

[www.prusaprinters.org]
(i don't see an input for idler pulley size)

For the record... I've ran the stock Folger pulleys (Y & X) since i got the kit and my prints are dead-on-accurate. I could put a 50mm pulley on my X Idler and as long as my firmware settings are accurate for my motor/belt/gear ratios it will have no affect.

Again... not arguing.. just want to make sure we are not speeding wrong information.

While I don't always (almost never) agree with Zav about calibration and measurements, in this case the problem exists, but ONLY if your belt along the top of the pulley, top of the gear and where it mounts to the y plate (or the x plate depending on what we're discussing) are not in a perfectly straight line (therefore making a triangle). what this does is change teh speed at which your bed will move from one end of the bed to the other simply because in a triangle, where the base is always the same shortening one side will lengthen the other side in a ratio that is not 1:1 and will therefore affect teh speed and distance that the peak of that triangle moves. As long as that is a perfectly straight line, then it won't affect the distance moved at all.

Again, as long as the belt is perfectly straight from pulley to gear through where it mounts to either the y axis sled or the extruder body, pulling the belt one way or the other will result in an equally straight and linear motion.

Although, to further complicate matters, the very small angle that you may be experiencing on your belt may be so small that the differences on the outer edges of your bed may not be that important to you.
 Re: Folger Prusa i3 Kit from ebay March 19, 2015 06:55PM Registered: 9 years ago Posts: 1,011
On my printer : +-0.2mm on a 20mm cube, noticeable through. Resolved with the new idler pulleys. I'm happy someone's took some time to understand Cheers.

Edited 1 time(s). Last edit at 03/19/2015 06:55PM by Zavashier.

Collective intelligence emerges when a group of people work together effectively. Prusa i3 Folger (A lot of the parts are wrong, boring !)
 Re: Folger Prusa i3 Kit from ebay March 19, 2015 09:28PM Registered: 9 years ago Posts: 116
I agree with Zav as well. So much so that I ordered the bearings last night. I believe that that little tensioning spring goes some way to making the pulley sustem work. Without it the belt would be changing tension along the way. Can anyone point me to where I could find a CAD model or something like that of this printer or at least the pulley system?
 Re: Folger Prusa i3 Kit from ebay March 20, 2015 10:26AM Registered: 9 years ago Posts: 110
Just curious but does anyone know the size or model of the v-groove bearing in the extruder? I replaced the extruder with MindRealms but it looks like my bearing is coming apart (the seal was off) so I carefully put it back together and closed it into the extruder and never looked for a model number or size and now I'm afraid that if I open it up again I'll lose some of the ball bearings out of it and be stuck so if anyone knows the size or model number so I can order a replacement (or several).

Also, where does everyone go for small parts (screws, bolts, nuts) I'm pretty close to being in the sticks and I'm having a hard time finding a local source for these smaller parts. I am thinking about setting up a second extruder with a bowden (possibly bowden both of the extruders) in an effort to reduce the weight for the X axis motor (though I'm thinking of beefing that motor up too when I rebuild everything using ABS printed parts and create my enclosure, finally) and will probably need a few handfuls of various size screws, nuts and bolts as I change configurations so any information on a reliable source that doesn't mind sending various counts of mixed parts would be useful here.

Thanks in advance
 Re: Folger Prusa i3 Kit from ebay March 20, 2015 12:22PM Registered: 9 years ago Posts: 14
Quote
louspinuso
Quote
TheLost
Quote
Zavashier
Quote
TheLost
Wait.. what?

Are you talking about the X & Y idler pulleys? (the only 'printed pulleys' included in the kit).. cuz.. the size of the idler pulley has no affect on speed/travel distance of the X or Y carriage.
Of course it affects if the system is not parallel. As far the pulleys form a triangle with the bet attachment, the travel is not equal to the travel around the driving pulley. That was the problem on my printer. See attached picture. If you still desagree, I don't want to argue. Ask an engineer you trust.

Not arguing.. Just curious.. (i took physics and mechanical engineering in college).

How does the idler pulley size change the distance the belt travels? (answer.. it cant)

[www.prusaprinters.org]
(i don't see an input for idler pulley size)

For the record... I've ran the stock Folger pulleys (Y & X) since i got the kit and my prints are dead-on-accurate. I could put a 50mm pulley on my X Idler and as long as my firmware settings are accurate for my motor/belt/gear ratios it will have no affect.

Again... not arguing.. just want to make sure we are not speeding wrong information.

While I don't always (almost never) agree with Zav about calibration and measurements, in this case the problem exists, but ONLY if your belt along the top of the pulley, top of the gear and where it mounts to the y plate (or the x plate depending on what we're discussing) are not in a perfectly straight line (therefore making a triangle). what this does is change teh speed at which your bed will move from one end of the bed to the other simply because in a triangle, where the base is always the same shortening one side will lengthen the other side in a ratio that is not 1:1 and will therefore affect teh speed and distance that the peak of that triangle moves. As long as that is a perfectly straight line, then it won't affect the distance moved at all.

Again, as long as the belt is perfectly straight from pulley to gear through where it mounts to either the y axis sled or the extruder body, pulling the belt one way or the other will result in an equally straight and linear motion.

Although, to further complicate matters, the very small angle that you may be experiencing on your belt may be so small that the differences on the outer edges of your bed may not be that important to you.

I understand all of that.. however..

1) The path of the X carriage is defined by the two parallel 8mm rods... A straight line.
2) The belt is a fixed size.

If you move the belt by hand 20mm.. the X carriage will ride horizontally along the fixed rods 20mm.

Having the left 'pivot point' (idler pulley) higher then the attachment point on the X carriage can affect speed and the max distance the X carriage can move.. but it won't affect how far it will travel. (because movement is in a straight line.. not up a triangle)

Again.. not trying to argue.. just trying to grasp what your saying.
 Re: Folger Prusa i3 Kit from ebay March 20, 2015 01:24PM Registered: 9 years ago Posts: 110
Quote
TheLost

I understand all of that.. however..

1) The path of the X carriage is defined by the two parallel 8mm rods... A straight line.
2) The belt is a fixed size.

If you move the belt by hand 20mm.. the X carriage will ride horizontally along the fixed rods 20mm.

Having the left 'pivot point' (idler pulley) higher then the attachment point on the X carriage can affect speed and the max distance the X carriage can move.. but it won't affect how far it will travel. (because movement is in a straight line.. not up a triangle)

Again.. not trying to argue.. just trying to grasp what your saying.

Yes, the bed will move straight because the rods are straight, however, the point where the belt meets the sled can change speed and distance moved based on the angle of the belt. You have to imagine that the length of all three sides of the triangle must remain the same length as the belt is a fixed length. Also, the base of the triangle must always be remain the same as the distance between the pulley and the bottom of the gear is fixed so the only things that change are the 2 sides that meet in the middle. If you shorten one leg by 10 mm, you must also lengthen the other leg by 10mm. This makes complete sense and is the easy part to follow, the more complicated part is that as you increase the angle (shorten a leg) of one of the sides, the apex of the triangle will move in that direction more quickly (fewer steps to move the same amount of distance will be required) therefore making the outer edges of your build platform susceptible to imperfect measurements.

Assume your belt makes a triangle with a base of 200mm and the other 2 sides are 80 and 150, splitting this into 2 right triangles gives you a triangle with a height of 53.198mm and the apex will be 59.75mm away from the corner in a straight line. If you now move 5mm from the side (moving the belt) so that the side that was 80 is now 75 and the side that was 150 is now 155, your new triangle has a hypotenuse is 75 (down from 80 because we moved 5mm) giving you a distance of your apex from the corner of 54 (was 59.75) which means that the bed actually moved 5.75mm, not 5 mm which could be quite a big difference, if the top of your triangle was 54mm above the top of the straight line that is made up by your pulley and gear. More than likely you are at less than 2mm (or maybe even none at all). At that height difference, making a triangle with a height of 2mm over a length of 200mm, you would probably only barely see the differences as you got closer to the edges. And if there is no height difference, then you're dealing with parallel lines and not triangles and then yes, moving 5mm of belt will move the center of your bed 5mm.

Further complicating matters, (because we can) the length of the belt for the bed is intentionally made to be longer than the bed to keep that point as close to center (and therefore closer to 1:1 movement in sloppy builds) as possible. The fact that we're dealing with such small scales and numbers practically make these movements silly to mention, unless you're working on extremely tiny parts with extremely fine and tiny detail (microbiology, probably) in which case you probably want something with a much finer print detail anyway and you're probably spending about 100 times, or more, than you paid for this printer.

Bottom line, for me, is that this printer is capable of printing things that are at least as good as I've seen some \$1,000+ printers print. Yes, I probably have spent more time tweaking and adjusting the printer than someone who buys a pre-built \$1000 printer, but for me that's 1/2 the fun. And once I got it to where I want it, the only work I do is upgrades and changing filament colors.

Hope that clears things up a bit.
 Re: Folger Prusa i3 Kit from ebay March 21, 2015 03:40PM Registered: 9 years ago Posts: 98
Hi fellas,

I finally received mine friday and have been sailing along pretty well so far. My main frame has a corner broken off so hopefully Folger will send a replacement. The acrylic was discolored where it broke so I'd guess someone hit it pretty hard to snap the corner off. My only issue so far is the Y endstop. The pictures don't jive with the the new revision B way of mounting bearings to the Y carriage so I can't mount the endstop like they want or the bracket for the endstop hits the bed adjusting screws. Anyone have a picture or can tell me how to work around this?

Thanks!
 Re: Folger Prusa i3 Kit from ebay March 21, 2015 04:03PM Registered: 9 years ago Posts: 10
I used this end stop holder works great , [www.thingiverse.com] Hits on the bed instead of the bearing

Edited 1 time(s). Last edit at 03/21/2015 04:05PM by Mudjunkie.
 Re: Folger Prusa i3 Kit from ebay March 21, 2015 04:08PM Registered: 9 years ago Posts: 98
Thanks, but kind of hard to use that without a working printer to print it lol. I like the idea though. Might be able to rig something up to make what I have work like that in the meantime.
 Re: Folger Prusa i3 Kit from ebay March 21, 2015 04:11PM Registered: 9 years ago Posts: 10
That's what I had to do, the end stop will work the way they ment it to it's just a pain getting it set
 Re: Folger Prusa i3 Kit from ebay March 21, 2015 04:16PM Registered: 9 years ago Posts: 98
Quote
Mudjunkie
That's what I had to do, the end stop will work the way they ment it to it's just a pain getting it set

Did you cut any of the length off for that bracket? I think that would help a lot but don't want to ruin it if I'm not thinking of something. Thanks
 Re: Folger Prusa i3 Kit from ebay March 21, 2015 04:19PM Registered: 9 years ago Posts: 110
Quote
krwynn
Thanks, but kind of hard to use that without a working printer to print it lol. I like the idea though. Might be able to rig something up to make what I have work like that in the meantime.

Not really that big of a problem. I had an older style end stop mount and couldn't get that mounted so I just held the end stop switch in place till the print started so that the printer could home and then put it down and let it just print. It won't look for the end stop once it starts printing.
 Re: Folger Prusa i3 Kit from ebay March 21, 2015 04:28PM Registered: 9 years ago Posts: 98
Quote
louspinuso
Quote
krwynn
Thanks, but kind of hard to use that without a working printer to print it lol. I like the idea though. Might be able to rig something up to make what I have work like that in the meantime.

Not really that big of a problem. I had an older style end stop mount and couldn't get that mounted so I just held the end stop switch in place till the print started so that the printer could home and then put it down and let it just print. It won't look for the end stop once it starts printing.

Ok. Thanks! One more question please. I've searched for an answer but haven't found one. The heat bed itself isn't marked as to what side is up or down and looks exactly the same on both sides. I'm assuming that the side where I can see the circuit running through the board is up. Just want to double check with someone before I commit.

Thanks for your help. Much appreciated.

Kevin

Edited 1 time(s). Last edit at 03/21/2015 04:36PM by krwynn.
 Re: Folger Prusa i3 Kit from ebay March 21, 2015 05:10PM Registered: 9 years ago Posts: 110
Both sides seem to get equally hot but you will need to put insulation under it (between the sled and heat bed). I find that the side without the LEDs is flatter and easier to set a Glass plate on.
 Re: Folger Prusa i3 Kit from ebay March 21, 2015 09:45PM Registered: 9 years ago Posts: 116
Did any of you file a flat onto the motor shaft to serve as a setscrew seat????
 Re: Folger Prusa i3 Kit from ebay March 21, 2015 10:54PM Registered: 9 years ago Posts: 98
Quote
Ecky
Did any of you file a flat onto the motor shaft to serve as a setscrew seat????

I didn't since there were 2 set screws for each connection.
 Re: Folger Prusa i3 Kit from ebay March 21, 2015 11:20PM Registered: 9 years ago Posts: 116
ok Thanks for the quick answer.

I am not able to zip tie the ends of Y axis belt together. No room for the zip tie. Anyone had any luck here.??
 Re: Folger Prusa i3 Kit from ebay March 22, 2015 09:18AM Registered: 9 years ago Posts: 53
oops....never mind; wrong issue... Thought you were talking about the 8 mm bearing rods being zip tied to the frame. For me, the bed does not clear those ties.

I did not attempt to zip tie the y axis drive belt, because it seamed retarded, to even try

[I have the same issue with the rear zip ties only. My temporary solution - until I install my new bed that is designed with linear bearing mounts in mind - was to limit that direction of the y axis to 188 mm.
As soon as I get those bearing mounts printed, I'll be replacing that acrylic bed, with the bed that came with the Reprap Prusa i3 improved 3d printer frame White Melamine coated MDF that I purchased from ebay. I didn't care much, for that flimsy acrylic frame that came with Folger Tech's kit.]

Edited 5 time(s). Last edit at 03/22/2015 09:55AM by 55rebel.
 Re: Folger Prusa i3 Kit from ebay March 22, 2015 06:14PM Registered: 9 years ago Posts: 116
Y Axis Micro Switch Position:

I have the model without the bearing supports on the bed frame, the bearing sit in holes in the acrylic frame, and I am unable to find a place for the switch to be able to touch the bearing or pretty well anything that makes sense.. How have you guys solved the problem???

Thanks

Edited 1 time(s). Last edit at 03/22/2015 06:16PM by Ecky.
 Re: Folger Prusa i3 Kit from ebay March 22, 2015 06:33PM Registered: 9 years ago Posts: 26
Quote
Ecky
Y Axis Micro Switch Position:

I have the model without the bearing supports on the bed frame, the bearing sit in holes in the acrylic frame, and I am unable to find a place for the switch to be able to touch the bearing or pretty well anything that makes sense.. How have you guys solved the problem???

Thanks
hi, I have the same bed model; i attached a picture. look how I put the switch. I hope it helps
 Re: Folger Prusa i3 Kit from ebay March 22, 2015 08:35PM Registered: 9 years ago Posts: 98
Great solution! Wish I'd have seen this hours ago.

Quote
pabloevaristo
hi, I have the same bed model; i attached a picture. look how I put the switch. I hope it helps
 Re: Folger Prusa i3 Kit from ebay March 22, 2015 08:51PM Registered: 9 years ago Posts: 98
Everything seems to be working ok. Endstops are behaving. Extruder heats up and feeds. Only issue so far is the heat bed. Got up to 50c and started going the other direction. Not sure what the issue is or where to even look. Connections are all solid.

-Kevin
 Re: Folger Prusa i3 Kit from ebay March 22, 2015 10:38PM Registered: 9 years ago Posts: 116
Quote
pabloevaristo

hi, I have the same bed model; i attached a picture. look how I put the switch. I hope it helps

Thanks for the picture. It looks like the microswitch is activated by the knob on the bed levelling.

Eckhard
 Re: Folger Prusa i3 Kit from ebay March 22, 2015 11:00PM Registered: 9 years ago Posts: 6
I had the same thing happen to me until I used Legos..they work real well...After about a week after the 16 day wait for the kit to arrive..I finally printed something..not sure what it is yet but I did it....I'll never believe a thing i read though because EVERYTHING seems to be backwards. If i wasn't mechanically inclined or a bit of an electrician I don't think I would have tried it. Now I'm hooked though and the Folger tech kit IS the way to go. You must have a basic understanding of how the systems work is all. Happy 3ding.

Edited 1 time(s). Last edit at 03/22/2015 11:08PM by Billygeorge.
 Re: Folger Prusa i3 Kit from ebay March 23, 2015 12:06PM Registered: 9 years ago Posts: 27
I just finished building my Folger Tech Prusa I3 rev B... I managed to briefly get the 3 axis to move a little in Ponterface, but over all it's not moving.. I also noticed that the Z axis was moving in reverse, but I saw a setting to fix that... I'm trying to use the latest Marlin firmware, but am having a bit of a hard time figuring out what settings I need to modify in the configuration.h file. Would someone mind sharing their configuarion.h file and telling me which values I need to change for where I have my ends stops placed?

X axis endstop is on the right
Y axis endstop is at the very front
Z axis endstop is at the bottom.

I figured trying to set them up as "minstops" according to the cartesian quadrant 1 system was the best idea to me.

Thanks in advance for any reply.
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