RepRapPro Mendel x axis assembly

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Revision as of 07:14, 11 July 2012 by Adrianbowyer (talk | contribs) (Step 3: Fit the X motor)
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A notice about these instructions!

Since 1st April 2013, the RepRapPro Mendel has been superseded by the RepRapPro Tricolour and Mono Mendel.
If you are building the new machine, use the official, and most up to date, instructions on the RepRapPro wiki here


Goal

By the end of this stage, your X-axis should look like this:

RepRapPro X Axis

Tools

You will need the following tools

  • M3 Allen key
  • M3 set screw Allen key
  • M3 spanner/nut runner
  • Long-nosed pliers
  • Tweezers
  • M8 spanner

Step 1: X carriage assembly

Reprappro-mendel-x-carriage-parts.jpg
Item Quantity
Printed X carriage lid 1
Printed X carriage plate 1
Printed X belt clamp 2
Cardboard heatshield* 1
Aluminium cooking foil* 110mm x 135mm
LM8UU bearings 3
M3x20mm screws 5
M3x35mm screws 5
M3x30mm hex-head screws 3
M3 nylock nut 1
M3 nuts 22
M3 washers 27

*Kits supplied from RepRapPro Ltd have the heatshield pre-cut from aluminised card. For those you can skip the next DIY section.

DIY Heatshield

Start by gluing the aluminium foil to the cardboard heatshield. The aluminium needs to go on the underside of the cardboard when the cardboard is the way up shown in the picture above.

Virtually any glue will do, but aerosol spray glue is easiest. Spray the foil, then drop the cardboard onto it and press it down against a flat surface.

Trim the foil about 5mm out from the edge of the cardboard and fold it over and stick it around the edge on the back. You can make a neat job if you make rectangular cuts of the foil by convex corners, and 45 degree angled cuts in to concave ones.

Let the glue set.

The Carriage

Next with the X carriage upside-down slide the LM8UU bearings into their holders sideways:

Reprappro-mendel-x-carriage-1.jpg

Don't try to fit the bearings by clipping them in from above - this will break the carriage. The bearings should be a snug fit. But if they are a bit lose, simply wrap a little Kapton tape two or three times round the lose bearing. Get it flat without wrinkles or bubbles.

Reprappro-mendel-x-carriage-optional-mounting-screws.jpg

Optional: Fit four 16mm M3 cap screws with four washers and nuts (not in the list above) to the carriage as shown. These are not needed at the moment, but will be used in future enhancements. If you fit them now, you will not need to take the carriage apart in the future.

Reprappro-mendel-x-carriage-2.jpg

Fit the hex-headed screws in their recesses in the flat plate. You may find it easiest to draw the hex heads into their recesses with a nut and washer on the other side of the plate which you subsequently remove. Make sure the hex head and the hexagonal hole line up before you start applying force.

Use the 35mm screws with nuts and washers to secure the plate to the carriage. Have the ends of the screws projecting as shown in the bearing-fitting picture above. Fit two additional nuts to each screw (making three in total) with two washers between each pair. These act as spacers for the heat shield (to be fitted later).

Put nuts and washers on the ends of the hex-headed screws.

Don't do these up tight. These screws allow you to adjust the relative heights of multiple extruders in the carriage.

Fit the belt clamps with screws nuts and washers.

Start by sinking the nuts into their recesses. You can do this most easily by pulling them through with a screw with a washer under its head. Make sure as you tighten the screw that the hexagon of the nut is aligned with its hexagonal hole.

The belt-gripping indentations on the clamps face the vertical pillars.

Fit the tensioning screw using the nylock nut as shown:

Reprappro-mendel-x-carriage-4.jpg

Step 2: Main X axis assembly

Reprappro-mendel-x-axis-parts.jpg
Item Quantity
Printed X end (motor) 1
Printed X end (idler) 1
428mm smooth 8mm rods (X) 2
8mm IGUS bearings 4
M3 nylock nuts 2
M3x16 screws 2

Start by fitting the IGUS bearing inserts to both ends:

Reprappro-mendel-x-axis-igus-check.jpg

You can curl them up so their ends overlap to insert them. Be careful.

Check their internal diameter by running one of the 8mm rods down them. If the rod is too tight (don't force it) put a 9.5mm drill bit shank in a vice, take the bearing inserts out, and slide the printed part over the drill to clean out the hole. Again be careful - you don't want to remove too much material and make a sloppy fit.

Repeat this process until the rod just fits and slides smoothly. It should not wobble from side to side.

With the tweezers fit the nylock nuts into their recesses in the idler end:

Reprappro-mendel-x-axis-idler-end.jpg

Pull them into their recesses with a screw if needs be.

Screw the two screws in by just three or four turns. Slide the smooth rods in so that they abut the screws and nuts.

Put the X carriage on the rods. Make sure to get it the way round shown in the picture.

Put the motor end printed part on the other ends of the rods. Make sure they slide right up to the closed ends of their holes:

Reprappro-mendel-x-axis-motor-end.jpg

Step 3: Fit the X motor

Reprappro-mendel-x-axis-motor-parts.jpg
Item Quantity
NEMA 17 motor 1
M3x10 screws 3
M3 washers 3
Toothed belt pulley 1
M3 x 10mm set screw 1

Later versions of Mendel have printed toothed-belt pulleys like this:

These simply push-fit onto the motor shaft - see below.

Use the screws and washers to mount the motor:

Reprappro-mendel-x-axis-motor-fitted.jpg

If you have a moulded pulley, screw the set screw into the toothed-belt pulley. Take care not to cross the threads - the plastic is not hard. Screw it in far enough to project into the hole down the middle, then back it off so it is no longer projecting. Blow any displaced pieces of plastic from the central hole. Put the pulley on the motor shaft with its hub outermost, as shown. Use the toothed belt to get it roughly the right distance along the shaft. Align the set screw with the flat on the shaft, and tighten it. Do not over tighten it - the pulley has an internal embedded nut, and over tightening will cause this to fracture the pulley.

If you have a printed pulley push it onto the shaft. It should be a tight fit, and you may have to tap it into place. Use a soft hammer, or a wood block. If you place a tube against the pulley that will fit over the motor shaft, you can tap the end of the tube to place the pulley. Support the motor shaft, not the motor body, from the other end as you tap. You can secure it with a drop of superglue if you like (make sure the shaft is completely free of grease). Take care that no glue gets near the shaft's entry to the motor.

Step 4: The X belt idler

Reprappro-mendel-x-axis-idler-parts.jpg
Item Quantity
35mm M8 threaded rod 1
M8 nuts 2
M8 mudguard washer 1
8mm bearing 1
M8 washers 3

Fit the idler:

Reprappro-mendel-x-axis-idler-fitted.jpg

From the right the sequence goes:

  1. Nut
  2. Mudguard washer
  3. Washer
  4. Bearing
  5. Washer
  6. Printed idler end
  7. Washer
  8. Nut

Next stage

The Z axis