I will set up X and Y to home to min, the back right corner. The XY steppers will be the rear of the bot, due to the single centered lead screw. 0,0,0 for me will be the center of the build plate. I believe that using ramps put the origin in a corner?

That switch looks perfect, it should fit nicely between the belt clamp and the nut for the mini-v. I may just mount the switch on the gantry plate, and cable it to the rest of the board elsewhere, I will also order one or two of those arduino switches to play around with. Adding a striker plate to the XY bar end was not too difficult, I am pretty happy with it.

 

Hey Carl,
I don't want to hijack the thread with my issue. I am going to start a new thread in the forums. I am too the point that I am going to put my fate in the hands of the open build community.
http://www.openbuilds.com/threads/help-me-get-my-prusa-i3-working-please.1227/

 

Hi,

Your speed settings are interesting, mine seem to be a bit higher.
I had lower from 450mm/s down to 100mm/s because I was having to much trouble getting the first layer to stick.

 

Hi,

What is the 1.8 multiplier, you've applied to the 60?

My settings are turned down till I debug why the skirt isn't sticking, the skirt setting doesn't seem to be controlled by the first layer setting.

Normally I have the settings about 450 mm/s and the none extruding speeds at 960 mm/s, but at these speeds it's a bit hard to see what is going wrong. I was expecting you would run at about these speed.

I don't bother with the acceleration settings, as they don't seem to make any difference to anything.

 

Hi,

I finally moved the end switch onto the carriage.


Here is my modified carriage back plate but I doubt it will be much use to anyone as my carriage is longer than normal to support by heads. Like Adamcoooks I had to add a flange to the XY Bar end, my one is on the other side, and I think I have the mount upside down, so it may need mirroring.

 

I think the griffin printer was going at some ludicrous speeds, something about molten filaments backing up into the bowden tube. 120 mm/ss, using direct drive dual extruders, seems to be the going rate for Fast in the clone world. My clone will print ABS that speed with pretty good detail, but it is highly modified with many plastic parts replaced with aluminum.

I did order some of those other endstops, I am not sure I got the order out before chinese new year shut down.

 

My other option was to remove the switch from the board and locate the board remotely. I like Nicks solution the best.

 

Yeah, don't worry about me, I don't know what I'm talking about.

There's something in Slic3r that is causing it to not work at the speeds specified. I printed my favourite cube with all the speeds set to 100mm/s and it took 41 minutes. I then set all the speeds to 200mm/s and printed again and it took 30 minutes. I was expecting it to take 20.

So getting rid of slicer and writing some G code, I discovered my top speed, without extruding, is somewhere between 250mm/s and 300mm/s, 250 works without errors, 300 had some skipping. I could probably tune it up to 300 if I took the time to fiddle. I have no idea why Slicer isn't adjusting the speed, when I can do it from G code, I'll have to see what slicer is putting out sometime.

So I made merry with the firmware settings, and got things up to the speed in bad.mov, this must just be on the edge of what can reliably be done as when I push it a bit further I get VeryBad.mov.

Eventually I wound it back to good.mov, which seems is producing some nice outputs.

Trouble is I have no idea what speed this is, as the settings don't seem to be making any sense . I'll have to retune it sometime, but at the moment I'm happy with the way it is running, it's making some very nice cubes...

 

It seems to be having some issues with the files.

 

Last part just ordered from sdp-si. Just a mock up, i need to rent a miter saw and a weekend with no snow to use it.

 

Gt2 belt, pictured is the open ended belt for the core xy I used to measure. Came out to 1870mm which of course sdp-di was out of stock. Two, closed loop, coming 1820mm and 1910mm I should be able to make either work by moving some idles around

 

I did shank the measurement though. Looks like if I want dual extrusion I will have to go bowden. I not completely sure I will acually be able to hit 100% of the HBP. I may loose 5-10mm of Y travel. My nozzle is further from the ganrty plate with the direct drive

 

I have a question, more on the Vrail side, I think you might have some insight on it. I am trying to figure out what cut vrail with. I am on the fence whether to buy a miter / chop saw or a tabletop band saw.

I used a 12" miter saw to cut the bulk of the frame, which i rented from Home D. It was a 700$ makita, and it was quite nice. I have an upcoming decking project, so I was able to slip a 12" miter saw from harbor freight past the wifecountant,. I did make a few cuts with it, to finish up my Z stage and crossmember for belt idlers, and I am not sure I want to keep it.

 

@Nick How tall is your Z axis? How much twist do you get?

I have some concerns with the amount of twisting I am getting with mine. Granted it is mostly only "mock up" straight, but it is firmly screwed together. My veritcal legs are 700mm. I am using the original Z ends with 1 row of wheels, I am thinking of adding a 20x20 cross member in between the steppers and the idler corners, mounted on the outboard track. Made me some 100mm corner brackets. I have been messing around with Fusion 360

@carl Do you remember the dimensions of the grooves you designed into most of your parts? the ones that fit into the vrail. I extruded the 10mm rectangle 1.5mm, then applied a 1mm fillet. It looks like it should fit nicely, but I wont have time to print anything for testing until next week.

 

My machine is 650mm from base to top. I've set the print area to 350mm, it seemed like a nice safe value to start with, and I haven't been bothered to adjust it.

There is absolutely no flex in the frame from top to bottom (left to right, or front to back).

Whenever I move my PursaI3 around it goes out of alignment and needs readjusting. I didn't what a repeat of this on this machine, so I went overboard with the corner bracing. Everywhere I can put a 5 hole-90 degree bracket has one, everywhere that can have a corner piece also has one, and if I can get both in it's even better.



I used the aluminium corners until we ran out of stock in Australia, and then switched to the printed ones. The printed ones worked as well as the aluminium for holding the corner, but give no sideways support but two together fixes this.

My build platform has a bit of flex in it, it seems that no matter how hard I try to get the play out of z axis wheel, when the have to take the weight of the build platform it compresses the wheels and flexes the wheel mounting bolts a little. It isn't much but with the leverage thing it becomes apparent when levelling the platform.


Another problem with the build area is it bounces, a tap on the front will cause it to bounce up and down a few times, this causes it to need re-leveling. I replaced the plastic mounts on the bar with aluminium ones, which reduced the bounce problem a lot, but hasn't eliminated it. It doesn't effect the print, unless I drop something on the front of the build platform.

You shouldn't have these issues because of your lead screw at the front of your built platform. This is something I'll have to look at doing in the future, I'm just monitoring your build to decide if I should use a belt like yours, or 4 stepper motors.

 

You could move two of the BP mounts to the sliding bar, it would move some of the weight off the cantilever. Have you considered a counter weight?

If I stand over my bot and grab it like a steering wheel, I can get a few degrees of deflection. I just ordered another stick of 20x20.

 

Nick, your Z bar is 20x60 if I can remember, would using the 60mm for your cantilever arms better distribute the torque to the 60mm of the Z slider bar?

 

Do you follow any formula for designing parts to 3D print. If you want a actual 16mm hole, what is your process of getting that out of the printer?

 

Carl
I have thought about this for days but I give up - how are the Z wheels adjusted on the rails??
I am implementing 4 ends and wanting to use only 2 wheels per end but I can't figure out how I will tweak them.
Do I need to design a different Z bar end for that? thx

 

I dont think there was any adjustment in the Z wheels, on my build the tolerances spot on, when I tightened the z plastic pieces to the bar there was very little torsion on the z slider bar. How are you going to lift the Z stage with 4 linear ways to avoid binding? I am also thinking about only using 2 wheels per side on mine, as there will be no torsion on the Z slider bar using 3 lead screw.

Is there any issue with having the grooves for three slots? your motor mounts uses dog ears to attach the horizontal bolts. I have attached a render of a lead screw base that Im fooling around with. my original conversion from motor mount to leadscrew base was kind of hackey ( done in tinkercad ) and now that I have learned a bit of fusion 360, im making a mk2.