wade extruder idler and springs

I've been trying to get the right stuff to build a wade extruder and I'm a little confused about how to attach the idler block. Some pictures seem to show the bolts with the heads in the recessed slots threaded side through the idler, some seem to go the other way. (perhaps with nuts trapped in the inside slots?)

Also, I'm trying to find out where to get the springs. I had ordered these from McMaster part number 9657K155 which are about 10mm OD but 10mm seems too large and they kept popping out, they also don't seem to have enough load according to the wiki. So I was thinking of ordering part number 9434K164 which is a lot stronger and is about 6mm OD. They're also pretty expensive, I guess I could just get some at a local hardware store, but they probably don't have a load rating...

I also ordered M4 wingnuts from mcmaster part number 94300A310 and although their website says they are 17.6mm wide, what they sent me was 22.5mm which makes them almost impossible to fit right.

It's really annoying to try and get metric parts here in the US.

In case anyone is curious, I'm building a list of mcmaster part numbers to order all the stuff needed for a wade extruder here: [spreadsheets.google.com] once I get this worked out, I'll post it to the wiki.

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Tony Buser http://tonybuser.com * http://reprap.org/wiki/User:Tbuser#Projects

I used just two hex head bolts in diagonally opposite corners. That leaves enough room for wingnuts. The hex heads do fit into recesses in the main body. If you put nuts in them you would need bolts just the right length as there is not much gap before you hit the motor.

I can't help with the springs as I just use some I had recovered from old equipment.

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[www.hydraraptor.blogspot.com]

Wade made his springs by hand using piano wire, I think.

I wonder, if you can't find springs, could you use Belleville washers?

Edited 1 time(s). Last edit at 06/04/2010 12:05AM by jbayless.

You can use springs from a BIC pen, though I don't know what the ID is of them.

I coudn't get long enough bolts at the hardware store so I cut some M4 threaded bar to 45mm (50mm is better), put some nuts on the ends and secured them with superglue. Those then went into the extruder body.
I think it is easier for the filament load to have studs sticking out the extruder body and hold the springs with washers and nuts opposed to removing bolts every time.

Old reply, but a few washers under the idler block lets you load filament on the fly. I left some extra travel in the design to allow for variations; reducing the idler block travel makes it easier to load filament.

Also, if you can't find strong enough springs, just bolting the idler directly will likely work, especially if you use only 2 diagonal.

You could also try using Belleville washers (disk springs).

[www.mcmaster.com]
[en.wikipedia.org]