Probably a dumb question, but how straight do the lead screws need to be? I just got mine in the mail, and of course they're bent. It's a good 2-3 weeks to get a new set which may or may not be bent, so I'm wondering if I should just try to straighten them myself, or return them and hope for better luck on another order.

 

Not sure if I just missed it but, has anyone done a z mount for a nut with 3 holes instead of 4? I have a delrin nut on the way with that configuration. 12.71mm OD and 25.4mm flange if that makes a difference.

 

May be you want to try with a flexible coupler first if it is not that badly bent..

 

Any has idea should i loosen the derlin wheel screws on both x end first before squaring the xy bar? i tried to adjust the xy bars (with wheels tighten) and find that the wheels on both sides seems to be skew against the groove of the v slot slope..

 

I guess it would depend on how bad. The ones I ordered were shipped with just bubble wrap around them stuffed into a bag. Of course, one was bent. The other was nice and straight. I ended up opting to carefully straighten it myself and got it pretty close. Between the designed play in the nut and the flex coupler, the Z still rides nice and smooth with only a little bit of wobble in the screw noticeable at the top. In my experience with other printers, as long as the deformation of the screw does not outstrip the ability of the nut and coupler to compensate, you should be fine. Of course, a perfectly straight screw would be ideal.

 

Thanks for the reply! I hadn't considered that it's going to be used with a flex coupler anyway. I'll hopefully have my steppers in tomorrow, so I'll wire everything up and see if it's acceptable. I'm mostly concerned that the Z height will vary over the course of a print.. I haven't built a printer that used a lead screw before, so I don't know what type of tolerance I should expect. I have them *mostly* straightened, though if placed on a flat surface they still wobble a bit if I roll them.

 

Well, proof is in the pudding. I have another printer I built that uses a single Z screw to drive the X gantry on two 8mm smooth rods. When the gantry is low on the screw and moving the top twirls in a very visible circle. The nut and coupler do their job well. It is my best printer and is my workhorse for special prints that need to be perfect.

Luckily with the C-Bot design, you can always change out the one screw after the fact without having to disturb the rest of the printer should you find it adversely effects your prints.

 

lol ... Never mind .... I found the OpenSCAD file ...... <duh>

 

Same except print bite

 

I had never heard of Print Bite. I see it is from the same folks that make the Flex3Drive. Looks excellent, if it lives up to the description on the site. I have used BuildTak on some of my printers with good success, but this looks like it has potential as well. Have you had the opportunity to try it out? If so, what are your impressions?

 

My impression so far have been amazing. I haven't tried ABS or Nylon yet but the PLA I have done has been perfect. The surface holds so well when its hot that you think you may not be able to remove the piece, which has happened to me multiple times with BuildTak. I could literally pick up my printer with 3DBenchy if I was so inclined. Once it has cooled to about 30 degrees centigrade you can pick the piece up off the plate as if it was never attached. It is so much more durable than BuildTak which I have ruined multiple sheets of by jamming my nozzle into it when leveling or printing too close, this stuff doesn't care. I love it. My Flex3Drive should show up in the next week or so too, crazy excited about that....

 

Nice! that sounds like a vast improvement. With BuildTak I have had to develop different techniques in order to preserve the rather fragile surface, though I do love it for PLA. For ABS I still prefer glass with ABS slurry. Love the way prints just pop off after the bed cools and leaves a mirror surface. Sounds like this stuff offers the best of both worlds. Might have to order some up and give it a try. Let me know if you try ABS. Very curious how the adhesion when hot combats the evil warpage factor.

 

Ah. I tried playing around with the project tool and couldn't get exactly what I wanted to happen. I imported the model into Fusion 360 and it was easy enough to do there, except there appears to be a problem with one of the two motor mounts. One is 85mm tall, the other is slightly off (0.052mm).


Looks like the Z height of what is the "top" of this motor mount is slightly raised off the bottom. The Z height of all the points on the correct motor mount are 0.175mm from the Z plane. On this motor mount, the vertex that forms the top corner is at 0.1765 which means it is slightly tilted upward. The bit that goes over the top of the 20x40 extrusion is orthogonal to that, so it is slightly angled too. This culminates in my problem which is that the face that has the hole for the belt to go through is angled toward the motor slightly. This can be observed by sketching a cube on the face of the motor mount section and extruding it up. 123D assumes this is a SUBTRACT extrusion because it sees you are intersecting with the angled face (because the top of the motor mount is at a right angle).



This is why I was having such a hard time extruding from either of the two faces and getting a piece that lined up properly with both of them. Unfortunately, I do not know how to fix this, because it seems like you'd have to tear down the whole mount just get re-do the original point that is not coplanar and caused all the problems. Any ideas?

 

I use PID on my "Fotek" SSR-powered 300x300 750W AC heated bed with a Smoothieboard and it never even gets slightly warm.

Nice thing about smoothie is that the PWM frequency is customizable per heater. I have my frequency set to 1.

Code:

temperature_control.bed.pwm_frequency        1

Which for some reason is not 1Hz, but closer to 1/3rd or 1/4 Hz.This turns the heater on and off with 8 bit resolution to the time, but the SSR waits until the next zero crossing to actually turn it on. This is sort of like bang bang in that it is on for a while then off for a while, but the temperature remains constant because the on period is, for example, 1.3 seconds then it is off for 2.7 seconds. With bang bang it goes up to 110C then cools down to 108C and goes back and forth heating up and cooling down.

It is interesting to note that the pwm_frequency is a float value so you can put 0.5 or 0.1 in there and get really long periods, but with 750W, leaving it on for 10s and off for 30s will give you pretty big spikes so 1.0 is a pretty good value.

 

How rigid is the surface? And is it possible to drill holes in it without it cracking/splintering/etc? I was going to pick up a piece of MIC-6 aluminum for my print surface, but if this stuff can be used on its own and it's as great as you say, I may just order it instead.

 

This is a fiberglass material so drilling holes in it is easy. It is only 0.8mm thick so you will sill need a base for it. I have a piece I have taped down on my 6mm tool plate (MIC6). The thickness of the aluminum helps spread the heat and keeps the Printbite heat even.

One word of caution. If you are using a 4mm inductive sensor for the Z axis, the bottom of the sensor is going to be a lot closer and could cause problems. I switched to a 8mm sensor and it stays out of the way now.

 

I haven't ordered an inductive sensor yet.. I thought I might try manually leveling first to see if I really need it. Is there a variant of the hot end that has an inductive sensor mount?

 

Sorry, one more question.. How thick should the aluminum plate be? I was going to go with 3/8" since that seems to be the sweet spot for pricing, but I'll go thicker if there's good reason to do so..

 

Not sure if there is or not. I did my own custom carriage to use a spare Printrbot extruder I had and designed an inductive sensor mount on it. There are some mount points on standard carriage that a mount could be put on.

 

I would say at least 6mm which is about 1/4". So 3/8" should be fine.

Where are you looking to get your plate from?

 

There's a chain called Metal Supermarkets that has a local location.. I figured I'd take in my heat bed so they could punch the holes in the right places. The online price was $55 for a 3/8" plate and $54 for a 1/4" plate, so I figured I'd pay the extra $1 for 1/8 inch of thickness.

 

I created my a differential IR sensor by completely copying the one for sale on Filastruder designed by David Crocker (dc42). They were $47 each at the time, and I wanted two of them so I said bump that and I recreated it from scratch in Eagle using the photos. I made it in 0805 though with mounting holes how I wanted them. Parts were about $2 from Mouser and the PCBs are about $1 from OSHPark as well. I ordered like 15 of them because I didn't want to place an order and force Laen to not be able to cover the cost of shipping!

You'll note that I spraypainted the back of my hardware store glass with high temperature black paint, because the MIC6 aluminum bed make the IR probe unusable due to how it creates a second reflection that can reflect internally in the glass and make even more reflections.



The mount is designed to come off once you've got the bed leveled (I only use it to probe around and then manually adjust the screws), but I leave it on and just disconnect the wiring (which is connected to the Z max endstop). If people are interested I can post the STL for the mount and a BOM. Also I have like 5 extra boards still I can mail people for free in the US.

 

I'd love to have one! I wouldn't mind paying for shipping/parts though -- otherwise I'll be sure to pay it forward next time someone needs something I can spare

 

I use Fusion and I have just started working with the parts in that. I would be down to convert it to Fusion and get it into STEP format as well probably. Need to finish up a couple of projects before I spend the time on it tho

 

Try this place: Cast Aluminum Tool & Jig Plate | Midwest Steel & Aluminum

I am using 1/4" and it works great, honestly I would just stick with that as its heavy enough as is. Here is the custom made heat bed that I literally JUST finished using Printbite, MIC-6 from that site, and a 120v silicon heater.

 

That's where I got mine from also. They had really good prices compared to the other places I checked. If I remember correctly, my 300x200 plate was about $60 with shipping. Shipping was actually more than the plate.

 

LOL yah. The plate is like $22.00 and shipping ranges from like $11 to $77