Prusa Mendel Build

[LeeWay]

I did fiddle with this a bit more yesterday. I was able to get it to home correctly and extrude. I was running this off a 24 volt supply though and got only erratic heating in the hot end. Fluctuated wildly. I turned it down to 17 VDC and it heated better. I had Pronterface set to 185 c and it would cycle between 205 and 182. I think it will all work fine once my regular 12 VDC supply gets here.
The motors were very strong @ 24 volts, but seem the same @ 17 vdc. Should run fine @12 too.

Just a word of warning here on the kits. It was likely just an oversite, but my opto's were not completed. They did have shrink wrap for the wires there, but they were not slid forward to the opto and heated. You need to pull back the larger shrink wrap on all these connections and look to insure the wires are covered. Could be very bad on the power or the Z motor pigtail.

The Wade's extruder is giving me fits again. It is poorly designed. The hardware just does not work like you would want. You have to remove and dismantle it to check if you have a clog. Can't really be done on the machine easily. With the supplied hardware, the stepper motor is in the way.

I ordered the Greg's extr. from Colin. That should help some I think.
I am going to get different hardware for the Wade's too. I will thread the plastic in the base to 8/32. Then screw in some long button head cap screws from the motor side into a countersunk hole. Then I will try some wing nuts. Another issue with it I think is there needs to be at least one small hole in the large gear to allow hex wrench access to the two hidden stepper screws.

Finally I think the smooth skate bearing contributes to filament slippage when loading especially. I am going to try to rough up the surface some on one and see if that has any effect.

I'll show some pictures and results when I get to that. It will be sometime next week though.

[Khalid]

Hi Lee,
thanks for detailing and posting about the 3D Printer. I request you to add more pictures and videos as you going on to the end.
Regards

[rwskinner]

The ones I printed looked good and fit fine, but I can't say they did much good: Mendel Frame Brace by ECsuyu - Thingiverse

I bet one like this would help a lot but I'm not sure I'm going to mess with it right now: Full crossbracing for Prusa simplified Mendel by Lanthan - Thingiverse

RIchard

Do you have a link to those?

[rwskinner]

Wow, and I'm using the stock Wade's Extruder with a Mark Iv J-Head and I think it's awesome. No plugs, no jams, no slippage. I love it.

As a matter of fact, I don't do anything but reverse it while it's hot to remove the filament then feed new stuff in without taking anything apart.

I do see you point about the two items though, I can see the hobbed bolt unless you take it apart and it's not easy because even though the nuts are captured they will fall out and it's hard to put them back in without sliding the stepper back.

The extruder's stepper and mount hit the Z axis carriage. Now it's built where you can cock it to one side or the other but that kills you Z height.

I do like the Gregg's version of it but I haven't printed it yet. I figure it's better to do in ABS than PLA and I just got my ABS.

Keep up the good work on your build and like Khalid said, lots of pictures.

Richard

The Wade's extruder is giving me fits again. It is poorly designed. The hardware just does not work like you would want. You have to remove and dismantle it to check if you have a clog. Can't really be done on the machine easily. With the supplied hardware, the stepper motor is in the way.

I ordered the Greg's extr. from Colin. That should help some I think.
I am going to get different hardware for the Wade's too. I will thread the plastic in the base to 8/32. Then screw in some long button head cap screws from the motor side into a countersunk hole. Then I will try some wing nuts. Another issue with it I think is there needs to be at least one small hole in the large gear to allow hex wrench access to the two hidden stepper screws.

Finally I think the smooth skate bearing contributes to filament slippage when loading especially. I am going to try to rough up the surface some on one and see if that has any effect.

I'll show some pictures and results when I get to that. It will be sometime next week though.

[LeeWay]

I think the magic lies in the hobing. My bolt appears to be hobed well, but along with the other shortcomings on the Wade's, it just isn't reliable enough.
I had no trouble extruding the 2' section of material I had in there for testing. Only when I went to reload did the problem arise. I'm sure the Greg's will fix it, but I want to do the mod's to the Wade's to help others that may find it difficult to use.

I am also looking into have a remote extruder that feeds through Teflon tube. That should make working on them a little easier as well. It would make for more waste when changing colors or types of plastic, but if it makes life easier, I think it might be worth it.
Hoss's thread has some links to those.

I am adding a couple of shots of my machine so far.

[LeeWay]

Here are a few images to show how I modded the Wade's extruder. Nothing much really. I did have some 6-32 x 2" flat head screws on hand, so used those rather than tapping the body for 8-32. Used nuts to secure them to the bodey and then just counter sunk the pinch roller holder for the nuts in the corners.
Now I can easily use even the stronger springs that came with the kit with no trouble. I have some wing nuts coming and might have enough room to use those on this. At least at the top side.

I also roughed up the center of the pinch roller to help add some friction to that side. I expect this one to work well now and be much more user friendly.

There was no room at the edge of the gear to drill a hole to access the two inside motor screws. I just snug them up good and force the motor over to engage the gears. Then I cinch the remaining two motor screws well. Mu flag for my optical limits bolts into the lower motor slot, so didn't need to drill an extra hole and it has some adjustment.

[LeeWay]

Thought I would share a very useful tool kit for building these machines.
This little screw driver kit from HF with a flexible extension is great for these.
It can get around to all the screws o this thing where big hands have a hard time.
My kit is a little newer than the one pictured and has a few more items in it. I paid $5 something in the store for it.
If you can find a kit like this, by all means, jump on it.
I can change out the extruder in no time now.

Precision Screwdriver Set - 33 Piece

[LeeWay]

A little more info on this and a few pictures.

I installed my Greg's open extruder and it works much better than the Wade's even after the updates I did on it. Clearly a better design for an extruder.

I ordered some Pet G rod from Mcmaster to do some testing with. This is 1/8" stuff and just does feed into the extruder correctly. Anything bigger would not work. I heated it to 200 C to start with. Well, it was good to start with, but then About 30 layers in, it started messing up and not sticking. Come to find out, it doesn't stick well to itself.
I could just about unravel the entire print like pulling a string on an old sweater. Definitely not what we are looking for. It did print nice and clear though without having to be dried. It should be dries though similar to Polycarbonate, but doesn't require such a long drying cycle. I will still try some other temps to see if it does any better, but so far, PET G is a fail.
Too bad. It was 19 cents a foot. Not a bad price. Terrible when it doesn't work though.


Here are just a few of the testing blocks and some of the parts I have done so far. All of these are PLA. I will install my heated bed tonight and start making some ABS parts.
I have designed a few parts in Turbocad so far. Bed leveling knobs and a couple other parts. I know they have them on Thingyverse already, but wanted to see what steps I needed to do nice STL's in TC.

I kept forgetting to convert it to metric. That is a deal breaker.
Gotta convert..... Gotta convert....

Anyway, here are a few parts.
I'll have more pictures of the machine soon.
Oh and those two black cubes in the foreground came out perfect dimensionally a look good print wise. Especially for pla without a heated bed.

[doorknob]

Just curious - How close do those black cubes measure up to the blueprint specs (using a caliper or, ulp, micrometer)?

[LeeWay]

Within 2 10ths of a mm. I don't think my calipers are actually that accurate. They are the ones I used to calibrate the axes with though so pretty darn close.

[rwskinner]

Mine generally come out within 0.003" or less but I can always count on max 0.003" and that is mainly because I don't spend anymore time on calibration.

Not too shabby.

Richard

[hoss2006]

Protoparadigm has some polycarbonate you could play with.
https://www.protoparadigm.com/produc...-3mm-filament/
I almost added some to my order but just got PVA and glow in the dark filament.
Hoss