Mendel90 Buyers Guide

There is a lot of supplier information for general RepRap parts in the RepRap Buyers' Guide. This page gives Mendel90-specific tips.

The Mendel90 build process will spit out a nearly-complete Bill Of Materials (BOM), telling you what you need to buy. Items not specifically listed in the BOM are:

• Ribbon cable (22- or 20-way)
• Thermistor (may well come with your heated bed package)
• Hot End
• Reel of plastic
• ...?

Nop head can supply a spreadsheet file with URLs to good UK suppliers for almost all parts.

Frame

DIY stores such as B&Q in the UK can often cut MDF to size for you. When you have found the size of the sheet you are buying, work out a cutting plan so they don't have to adjust their machine between cutting two items of the same width, such as the base and gantry. This'll make sure they match exactly.

Fasteners

As the main page notes, this design requires a lot of different fasteners. To keep the cost reasonable, you will need to order them from a supplier which does small quantities. Try hard to find one which supplies in labelled bags - Orbital Fasteners is one such company. As the fasteners are so cheap, it is suggested that you order 2x the amount for anything in quantities of 4 or less, and "a good few extra" for anything in larger quantities. This will prevent you having to panic if you drop one on the floor, and give you flexibility for later fixes and additions.

If you plan to hob your own bolt, it would be a good idea to order several so you can practice. That's the 60mm M8 hex screw.

Rods

See if the company supplying your smooth and/or threaded rods can cut them to size. It makes life so much easier. Zapp Automation in the UK will cut their smooth rod to size if you specify it in the order notes.

Springs

Springs are hard to source at a reasonable price. Getting the right spring is more crucial for some than others.

The big one is not critical at all as all it does is stop the M8 nut vibrating off. You could use a Nyloc or two plain nuts instead. The spring allows you to remove the nut with your fingers.

The extruder springs are more critical in terms of length and wire gauge. For example some which were 12mm long and 1.15mm gauge were too strong and crushed the filament. The force is proportional to the fourth power of the gauge and the distance compressed. The length of the bolts means you can't use longer springs. Longer bolts stop the carriage meeting its endstop. The outside diameter is not important, but the inside diameter has to be bigger than the bolt inside and it is OD - 2 * gauge.

Hot End

To be filled in. J-Head Mk IV is what nop head uses, but they are no longer in production.

Other tips

The big ticket items are the electronics, the motors, the hot end and the set of printed parts. Nop head supplies printed part sets, or if you have a friend with a reliable existing Reprap, you could ask them to help you out. Different electronics come at different prices, but if you want one that will power the fan (which is optional) you'll need a more expensive set. Gerv's parts cost £500 in total.

10cm is actually a tiny bit too short for the zip ties; get 12cm or more. (This needs to be fixed in the BOM generation.)