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Discuss any sort of mechanical stuff here: positioning systems, gears, extruding methods, etc.
MatWeb Parameterized Search - 18 years ago
I just remembered an interesting web app I found some time ago: You can select a type of material (e.g. thermoplastic) and then specify up to 3 characteristics you need. It'll spit out a list of matching materials. By the looks of it, it has over 30000 thermoplastics in its database. I didn't see polycapralactone in there, though.by degroof - Plastic Extruder Working Group
Re: Materials which can be used - 18 years ago
So, what's our "ideal" material, then? Something cheap with, say, the consistency of nylon at room temp, a melting point slightly above 100C and zero shrinkage?by degroof - Plastic Extruder Working Group
Re: Resistance Calculations - 18 years ago
Makes sense. And the scale factor can be explained by cap tolerance. It's entirely possible it's off be ~10%. I guess I could compensate for the impedance by adding it to the original resistance measurements and plugging that into the beta/Rz formula. But, yeah, it might be better in the long run to have it as a parameter. What I'm shooting for is getting reasonably accurate temperature readinby degroof - Reprappers
Re: Resistance Calculations - 18 years ago
Ah, so that explains it. The 144 figure is really the only anomalous value. The rest scale properly (.88-.9) but the should've translated to 90-something. The 101 ohm value was a bit on the small side anyway. It works out to about 360C for the 100K thermistors. I'll try again using a larger value.by degroof - Reprappers
Resistance Calculations - 18 years ago
I tried an experiment. I took a handful of resistors, measured each with a multimeter, then attached each to the thermistor connector. I used the RepRap host software in debug mode in eclipse to look at what it thought the resistance was. Here are the results: Real Measured 101 141 6650 6020 26900 24140 46200 41180 99000 87000 What it comes down to is that there's a scale factor plus an offset.by degroof - Reprappers
Re: Win XP communications problem - 18 years ago
I just checked my setup. I have "COM1" as the port name. If I change it to "com1", it fails with "there was an error opening com1". I'm guessing it has to be uppercase.by degroof - RepRap Host
Re: Thermistor Mounting - 18 years ago
I just slip it over the heater barrel and tighten the nozzle over that. The heater's wrapped in PTFE tape, so the ring's wedged between the two.by degroof - Plastic Extruder Working Group
Re: Troubleshoot Power Comms 1.3 Board - 18 years ago
Just the 12V should be OK. I'm using a 12V-only supply from an old project I dismantled.by degroof - Controllers
Thermistor Mounting - 18 years ago
After seeing RoundSparrow's post here I tried something similar using a 3/8" washer. Bigger than a penny but it already had a hole in it. Acted like a heatsink, though. I also tried using a bent paperclip. That seems to work nicely.by degroof - Plastic Extruder Working Group
Re: Reprap Host 0.8.3 released - 18 years ago
> - The "line test" routine seems to move only one > stepper. Either X or Y but not both at the same > time. Ah, apparently it helps if you actually connect the sync lines. Oops.by degroof - RepRap Host
Re: Thermistor Calculator - 18 years ago
Sure. All the code is contained in the page itself (i.e. no includes), so it should just be a matter of copy and paste.by degroof - Reprappers
Re: Extruder Construction - 18 years ago
Well, the official way is to solder it: I couldn't get solder to stick to it, though, so I went with nophead's technique:by degroof - Mechanics
Re: Changes that need to be made to the extruder - 18 years ago
nophead Wrote: ------------------------------------------------------- > Yes, but what happens when you want to stop? One > end of the AL is at 660C, the heater is off but > that heat will travel back up the stock. It will > reduce in temperature as it travels though. Would it help any if the aluminum were discontiguous? Say you used aluminum powder and gradually dropped small amountby degroof - Plastic Extruder Working Group
Thermistor Calculator - 18 years ago
I made another calculator: This one will calculate beta and Rz for a thermistor. It also has a simulator where you can plug in beta, Rz, C3 and a temperature. It'll spit out what the RepRap host software would read as the temperature. For example, if you plug in the standard values of 3480, 32660 and .00000001 for beta, Rz and C3, the temperature tracks very well up to about 100C. After that,by degroof - Reprappers
Re: Review of alternate Thermistor part options? - 18 years ago
I got 5 of the 5% 100K thermistors from Digikey yesterday. A quick check shows that, while the beta and Rz varied from piece to piece, each one was consistent. They seem to work the same way as resistor tolerances in that, if you've got a %5 part and they also sell a 1% part, yours is going to be somewhere between 1% and 5% off the spec values. If you don't mind doing a bunch of measuring and cby degroof - Plastic Extruder Working Group
Re: Changes that need to be made to the extruder - 18 years ago
I was thinking of adding a ridge to the clamp and cutting a groove in the PTFE but I like this better. It means you can eliminate the bolt and turn the clamp into a solid piece. Fewer points of failure.by degroof - Plastic Extruder Working Group
Re: Too many forums now. Subforums or use message subjects - 18 years ago
nophead Wrote: ------------------------------------------------------- > So that's why Google reader is giving me stuff I > have already read. Yeah, I noticed the same thing.by degroof - Administration, Announcements, Policy
Re: Using pre-packaged gooey stuff - 18 years ago
Wacky idea: Could an optical mouse be used to track the rate of material coming out of the nozzle? As I understand it, an optical mouse is essentially a tiny, short-focus camera hooked up to a DSP. The mouse might be able to interpret the motion of the extruded material as mouse movement.by degroof - Plastic Extruder Working Group
Re: "Kiosk", by Bruce Sterling - 18 years ago
I was just about to post the same link. I've only read a couple paragraphs. The rest'll have to wait until after work.by degroof - General
Re: RRRF membership objectionable clause - 18 years ago
It's not a blob; it's a "value-added product". :-)by degroof - General
Re: Unreprapable RepRap Parts - 18 years ago
There's a new page with parts modded for single-head printing here:by degroof - General
Re: How is it made? - 18 years ago
It's PTFE (Teflon). There's a set of DIY instructions here:by degroof - Plastic Extruder Working Group
Re: Changes that need to be made to the extruder - 18 years ago
I think I can help with #1. I've got models of both the original and quick-fit extruder clamps that *should* be printable on a RepStrap (i.e. they look OK but they're untested). I can add a ridge to the inside of the clamp. I'm thinking, say, half the height of the clamp itself, with an inside diameter of 14mm. To use, you'd need to cut a 2mm-deep groove near the end of the PTFE and snap it intby degroof - Plastic Extruder Working Group
Re: Plastic Pooling in Extruder Barrel - 18 years ago
The two screws seem to hold everything in place. What I'm planning on doing is, once I have a working Darwin, one of my first projects will be to make a new extruder. I want to put a ridge on the inside of the clamp and then cut a matching groove in the PTFE. I've also noticed a bit of sagging of the extruder body at high temperature, so I'm thinking some support struts might be needed. Right noby degroof - Reprappers
Re: Web Fighting - 18 years ago
It sounds a bit like the Traveling Salesman problem. You want the head to cover a given area without retracing its path and without crossing voids.by degroof - Plastic Extruder Working Group
Re: Reprap Host 0.8.3 released - 18 years ago
Looks good. I was able to control the stepper motors and it correctly sensed room temperature. I didn't mess with the extruder, though. A couple minor things I've noticed (they're also present in 0.8.1): - The "line test" routine seems to move only one stepper. Either X or Y but not both at the same time. - Seems to be a memory leak or something. If you keep doing build simulations, you eventby degroof - RepRap Host
Re: Reprap Host 0.8.3 released - 18 years ago
I downloaded it this morning, just before heading to work. One thing I noticed is that it's much more robust in handling narrow regions and acute angles. I was getting a lot of null pointer exceptions and "resolution limit" messages with 0.8.1. The ugliest STL I've got right now is a modded version of the diagonal tie bracket. It has all sorts of fiddly bits (technical term). The 0.8.1 app can'by degroof - RepRap Host
Re: Bulding the extruder HELP!! - 18 years ago
The wire is probably pretty close to 8 ohms anyway. If you measure it and it looks a bit high, you could lower it slightly by removing a bit of insulation and moving your contact points closer to the barrel. I think the nichrome is about 1 ohm per inch.by degroof - General