Gina

Photo of the Z level adjuster wheels - top and bottom.

Made a mistake in the design of the back bearing blocks. Needs the bearing 10mm nearer the edge. Re-design coming up...

Production is progressing well The so-called 1000mm rods are actually about 10mm shorter but that doesn't bother me as I shan't be using the whole metre anyway I though the little holes round the edge of the nuts were threaded but they're not. Just plain holes about 3.5mm diameter. I had planned to attach adjuster wheels with screws but instead I think I'll just 3D print pegs on the wheels instead. No problem and saves assembly time. I shall print the adjuster wheels on my Mini printer for greater resolution and I can do that while the Titan is printing the nut blocks.

Nuts are 12mm diameter shank so that was a good guess Now printing one of the nut blocks.

Managed to get inside and get the rods and nuts out

The rods have arrived but I'm having trouble getting into the packaging!!

Now printing in rigid.ink transparent orange like the rest.

Back Z Drive Bearing Block.

LH Front Z Drive Bearing Block.

RH Front Z Drive Bearing Block.

Yippee! Trapezoidal screws and nuts are out for delivery. Just hours to wait now

Here is a starting design for the LH back trapezoidal nut holding block. The big hole is to take the shank of the nut and a guess ATM. I think the RH back block will be the same but inverted. The thickness of the top and bottom parts of the block provides spacing for the XY timing belt idler pullers. These are the holes that are offset top to bottom, the other holes are for fastening the block to the frame. The gap is to take the rails of the frame and should be a nice snug fit.

Here's a better photo. This is from the RHS - the front of the printer is on the left of the photo and the back on the right. ie. the motor will be near the back. I have taken the XY frame with carriages, motors etc. out of the frame.

I have a test setup installed on the acrylic sheet for a timing belt and pulleys and checked for the best place for the Z drive stepper motor. Here's a quick photo - not very good I'm afraid. Distortion is due to wide angle on zoom lens.

I've attached a 2ft (610mm) square acrylic sheet to the top of the frame. It's a bit short as the width is 740mm but I can fill that in with something. I couldn't find a source of 740mm or 750mm x 610mm as this is basically a mix of Imperial and metric. (610mm is really 2 feet and a size of shed window). At first I was going to place it centrally but the supports would interfere with the Z drive.

Been looking into the Z drive system and laid out the pulleys and one of the belts on the acrylic sheet on the top of the printer. With the rods where I'm thinking of near the inner corners of the XY frame, the belts may not quite be long enough with the motor over near a side. As the motor is moved towards the centre of the top, the belt length required reduces which leads to a slight change as shown in my latest digram below. I can't really make parts until I know the exact dimensions of the nuts.

Just checked the delivery tracking and the estimate is for tomorrow (24th April) and the shorter ones for my Titan printer upgrade have been included in the same package That's rather better than the original delivery quoted for the 500mm rods to fit the Titan printer

The problem with just two wheels may be that the frame could go off-square. The second pair of wheels were to prevent this. Hence the design with four wheels and four rods allows for any lack of rigidity in the corners of the XY frame.

Here is another idea for the Z drive belts and pulleys which uses just two idler/adjustment pulleys but still provides good wrap around the pulleys. The motor has two pulleys and the belts are at different levels. I've added a second diagram showing just one belt round the motor pulley.

Here are a couple of diagrams - first the arrangement I have ATM and the second with just two wheels.

I think you have understood my design alright. I think you are right that two V-Slot wheels would be sufficient to constrain the Z carriage in the XY plane.

Checked the maximum printing area with the new carriages and it's 450mm x 415mm (X x Y). Can't yet say what the height will be but 600mm looks likely, possibly more.

I think the easiest way to adjust the Z carriage for level (to get it well within the limits of the automatic bed level compensation) will be to have thumb wheels on the trapezoidal nuts, maybe with clamps to hold them in position once levelled (vibration could cause movement otherwise).

I think the next job is to sort out the Z drive. The trapezoidal screwed rods will go in the corners just inside the XY frame (Z carriage). I plan to mount the associated nuts in 3D printed brackets fastened in the corners of the XY frame. At the top will be ball bearings mounted in 3D printed brackets attached to the main frame, to take the screws with a short spacer and timing pulleys (60t 8mm bore). As shown in a diagram above, the four pulleys will be driven by a pair of timing belts on a pair of 60t pulleys on the Z drive stepper motor, mounted in the middle of the top. Idler pulleys will provide for tensioning the belts and also improve the amount the belts wrap around the motor pulleys.

More photos.