scratch built rep rap in progress

Decided to have a go at making a printer my self I maybe out of my depth but I thought I'd give it a try I fancied Tring to make an aluminium framed one as I have access to a lot of materials at work what do people think

Where did you order the bearings?

Ebay from china £10.00 for the 4

If you're planning on printing with ABS, plan on enclosing it and keeping the electronics out of the enclosure so it can be operated at elevated temperature. I think you've got a good start. Try pushing on the frame. If it flexes perceptibly, make it stiffer. If it flexes when you push on it it will move when a bed or extruder carriage is moving back and forth. If the frame flexes print quality will suffer.

Cheers for the advice a inclosed box was an idea at first but I decided to keep it open until I had a working model then maybe I might enclose it still Tring to work out how I'm going to make the x axis as I'm Tring to avoid plastic parts as much as I can

Here is my current X-axis design- very modular and scalable. I uses a linear guide screwed to a 1" square aluminum tube and NEMA-23 motor- you can probably use a NEMA-17 motor. The X-min limit switch is on the motor mount and is bumped by the linear guide bearing block. The belt tensioner/idler has a mount for an X-max switch if you want to use one. This assembly bolts to the Z axis screws in my printer. I had a little delam in the motor mount because it was printed without an enclosure on the printer- I'll probably replace it with an all aluminum version soon.

Linear guides provide a very compact and very precise means of moving the extruder carriage. You can often find good deals on used ones on ebay.

Can you show what the linear guid setup you used looks like, curious how you did it with only one rod screwed to that square tube.

Linear guide has a single rail that has grooves for balls on two sides. The bearing blocks have two loops of recirculating balls on each side. Here's an example: [www.ebay.com]
These things are usually precisely machined and ground and there is very little play (as in undetectable without good measurement instruments) in the motion of the bearing block that rides on the rail. I used NSK LS-15 linear guide. The square tube is probably not necessary because of the short run in my printer- the guide wouldn't sag enough to affect print quality if it were unsupported, but the square tube makes it easy to mount the whole thing and add other parts like motor mount, belt tensioner/idler, and Z axis zero screw (the thumb wheel on the left)..

I had to use a grinder with a cut-off disc to cut the rail to length- the steel is so hard I could barely scratch it with a hack saw or band saw.

You might also want to check out the dozens of you tube videos on building a scratch built printer. Lats of people have made interesting mistakes and come up with interesting solutions.