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RepStrap Recipe?

Posted by BeagleSeven 
RepStrap Recipe?
April 15, 2012 01:23AM
I have come to the conclusion that I'm going to have to do everything from 'scratch', for a long list of reasons.
The lead items are:
1. Puny finances
2. No suitable machine tools
3. No vehicle
4. Located far away from the nearest *active* Reprap group

I am wondering about building an Eiffel type device but with the type of extruder in the FTIstrap. Any comments on that idea?
Thanks
/Dave

Edited 2 time(s). Last edit at 04/15/2012 05:45PM by BeagleSeven.
Re: RepStrap Recipe?
April 16, 2012 03:49AM
I had the same idea, but it ended up costing about the same as a kit in replacement parts/ failed parts/ time spent.

THe most expensive parts are going to be the motors and electronics, and you can't make those yourself anyway. And getting threaded rods/drill rods is going to be pretty expensive unless you scavenge old printers, but you can't count on those having the same rods/the right rods anyway, and you still need the threaded rods (or other frame elements. Still expensive). I ended up choosing to make a mcwire bot, but not knowing much about 3d printing that ended up being a very bad idea (super slow, super annoying to align). Plus those pipes the frame is made of aren't cheap either.

Making an extruder capable of extruding ABS or PLA is actually a lot easier than you'd think. I've made all the parts to my extruder myself using only a drill press and a file (well except the motor and the gears). One useful strategy I've learned is, if you have any sort of plastic gears you've scavenged from stuff, you can melt them onto a motor shaft and they stay on REALLY well. Just drill out the gear to slightly smaller than the motor shaft, and heat up the motor shaft with one of those cigarette lighter soldering torches from home depot and press the gear on. The same trick works for carriage bolts (the ones with the square part and a round cap). I used VEX gears for mine (pretty cheap? [www.vexrobotics.com]) but I'm sure that the technique works with any plastic gears.

So if I were you (and myself, three years ago) I would get a kit (maybe just a hardware kit, if you want to make the "printed parts" yourself. But you have no machine tools so maybe not) There are some FAIRLY REASONABLE and PROBABLY WORKABLE ones out there these days.

Also if I were you I would invest in a drill press. Most. Useful. Tool. Ever. I can't tell you how much of my repstrap I made on that thing (pretty much all the hot end parts... I did a lot of machining on it). AND from harbor freight drill presses are super cheap (like $35). Totally worth it.

Good luck! Be sure to document your process it might help others know what they are getting into grinning smiley

Edited 2 time(s). Last edit at 04/16/2012 03:56AM by destroyer2012.
Re: RepStrap Recipe?
April 19, 2012 03:00AM
Thanks for the comeback!
Re:
"And getting threaded rods/drill rods is going to be pretty expensive unless you scavenge old printers,"
Actually, I am a Freegeek volunteer; they go through (literally) tons of printers per month.
I know there is a supplier of the "vitamins, here in Canada, but they don't have any printed parts; that's what's holding me back.
I can get the use of a drill press and lathe, probably.
Haven't looked at the electronics lately - are they using multi-layer boards? (Besides the Arduino)? /Dave
Re: RepStrap Recipe?
April 19, 2012 06:44AM
Some do, some don't. Gen7 is designed for home fabrication, gen6 is designed for profesisonal fabrication, RAMPS 1.2 can be etched at home but later versions need to be done professionally and 1.4 requires SMD soldering. It can be done with regular soldering equipment once you get the knack of it, I'd rather buy one assembled.

For printed parts, emakershop.com may be your best bet. Theres no canadian supplier but a number of US suppliers.
Re: RepStrap Recipe?
April 19, 2012 08:20AM
I made my reprap corner pieces from 18mm marine ply and the stepper motor holders from 10mm ply.

The extruder is made from a 10mm plastic kitchen cutting board in 3 parts and superglued together.

The gears are also made from the same cutting board.

The cutting board cost $10 and I had enough left to make several gears or another extruder.

The hobbed bolt was a piece of threaded bar left over from the cutting list.

The electronics will be the dearest. Mine just arrived in the mail from the uk and cost about $160

Parts list to date is....

Threaded bar and stainless bar. .................................................................................................$ 30
Lm8uu linear bearings from ebay Item number: 260968344745 ............................................$ 15
Sanguinololu 1.3a Complete electronics board Ebay Item number: 220975353571 ...........$160
Stepper motors about $25 each times 5 ...................................................................................$125
From reprapping on ebay
Hot end with resistor and thermistor .......................................................................................... $ 45
Hot bed.......................................................................................................................................... $ 25
T5 belts and pulleys...................................................................................................................... $ 10
ABS fillament ebay Item number: 120893061069.....................................................................$ 55
Freight........................................................................................................................................... $ 7.50

Total ...............................................................................................................................................$ 472.50

You could save $90 on the electronics if you order the kit unassembled with the smd installed and $30 if you can source the threaded bar and smooth bar from old printers or build a repstrap frame from wood and then print reprap parts from that.

You could save on the hot end if you make it yourself. There are lots of good tutorials on the subject.

You can get away without the hod bed if you use Pla for a while.

You can use bushes instead of linear bearings.

So there is the potential to save over $205 which would bring it down to about $270.

When I get it running, I will repost with the success ( or failure ) of the cutting board extruder and gears.

My ultimate goal is to find sources of the cheapest material possible or reuse as many old parts as possible, Hence the cutting board extruder. The next printer will be made differently. Maybe a repstrap from wood to see how low price this can be done. If I solder my own electronics, I will post full details as this is one of the biggest savings possible.

Pics included.

Hope this has helped.

Greg

Edited 1 time(s). Last edit at 04/19/2012 08:34AM by gregted.
Attachments:
open | download - 3d printer bare small.jpg (330.9 KB)
open | download - Cutting board extruder2.jpg (434 KB)
open | download - Cutting board extruder3.jpg (413.1 KB)
open | download - Cutting board reprap gears.jpg (410.1 KB)
Re: RepStrap Recipe?
April 19, 2012 01:05PM
For Canadian palstic parts, I'd recomend:

www.eckertech.com
Re: RepStrap Recipe?
April 20, 2012 03:06PM
Thanks for responses!
I have a couple of extra questions:
1) What is a 'hobbed bolt'?
2) Any comments on A2A Parts?
/Dave
Re: RepStrap Recipe?
April 20, 2012 03:38PM
Hobbed bolt


Bob Morrison
W├Ârth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse
Re: RepStrap Recipe?
April 20, 2012 08:06PM
A hobbed bolt is a bolt or in my case a piece of threaded bar that has been ground with a grinder and then a small 5mm or similar tap to give the bolt teeth to grip the filament. First photo

Another great idea from others I have used on mine was to cut the thread along the bolt in places with a dremel tool to turn the thread into teeth. This grips like a bastard. Photo 2


Good decisions come from knowledge, knowledge comes from bad decisions,
Attachments:
open | download - Hobbed bolt.JPG (19.1 KB)
open | download - Hobbed bolt-cut.JPG (23.2 KB)
Re: RepStrap Recipe?
May 24, 2012 05:16PM
> When I get it running, I will repost with the
> success ( or failure ) of the cutting board
> extruder and gears.

Any luck getting it all going?
Re: RepStrap Recipe?
May 26, 2012 04:02AM
Hey conscripted,

I did get my printer "Woody" running but I decided to chicken out from using the cutting board extruder at the end because I really wanted to see it running with the other wooden bits I made and it runs great.

I will include some pics of the quality of the prints I am getting.

It works so well that I got the proper t2.5 gears and belts in the mail instead of Woodys' t5 belts and the original stepper motor gears that were on the motors when I bought them that I think I will leave them alone and put these on my next printer.

I will try the extruder I made at a later date on another printer.
Attachments:
open | download - X carriage.JPG (292.8 KB)
open | download - Large herringbone gear.JPG (297.9 KB)
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