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3D printer build log

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Joules:
You will be 3D printing covers to tart up those holes.  :lol:

spuddevans:

--- Quote from: Joules on May 24, 2017, 02:01:54 PM ---You will be 3D printing covers to tart up those holes.  :lol:

--- End quote ---

Probably. I would weld them up a bit, but I'm afraid that the welding would cause too much distortion in the frame. Anyways, they will be almost hidden when the whole project is complete and enclosed.


I managed to grab a few mins in the workshop today and drilled and tapped for M6 grub screws to grip the 8mm ground rods. Then I drilled and tapped some M3 holes to hold the 12mm linear bearing in the carriages. (I drilled/tapped 1 hole at each end, carefully positioned so that the M3 washer is just protruding over the edge of the bearing)




View of the M6 holes (I counter-bored 6.2mm to a depth of 20mm, leaving approx' 9mm to tap M6, much easier to tap)



Onwards and sideways

Tim

PekkaNF:
This is very interesting thread.


--- Quote from: spuddevans on May 26, 2017, 01:20:33 PM ---.....
Onwards and sideways
--- End quote ---

I was told " Wet fly - down and across" :wave:

Pekka

spuddevans:
Well, it's amazing how life can get in the way of building a 3D printer!!!

So after quite a looooong break from this project, I've been getting back into this again. There's not a huge amount to show from the last few weeks, but I've been getting a few small items ticked off the "to-do" list.

Here's a shot of where I'm up to at the moment, I've been working on the Z-axis which is based on 3 leadscrews coupled with some 8mm smooth rods. This is a poor semi-overhead view


I made a frame consisting of an upper and lower sections of 25mm box steel, well actually I made 2 frames, one for the front and one frame for the back, and these are where the Z-axis guide rods and leadscrews will be held in.

The leadscrews have been turned down to 8mm at their ends where they go into the 25mm box-section steel, and for each leadscrew there are 2 flange-bearings (countersunk one each on the top and bottom sides of the box-section) which keeps them running smoothly, and the 40t pulleys are also 8mm bore.

I very precisely drilled and bored the 25mm box-section frames for each set of holes (for each front carriage there is one guide rod exactly 25mm centres from the leadscrew, for the rear carriage there was 2 guide rods, both exactly 25mm centres from a central leadscrew). There are 2 lengths of 25mm box section in each frame, one set for the rear, and one set for the front. Each set were drilled and bored together to ensure alignment was kept accurate.
The 25mm box-section frames were carefully milled to length to be a precise, snug fit into the main printer frame, and thus they only need a M4 screw at each end to hold them in place. (they actually hold themselves in place without the screws, but the screws make sure that when everything is moving and warmed up, nothing will move)

The Z-axis carriages are milled out of aluminium bar, here's a shot of one of the front 2 carriages taken from below (the other 2 holes are drilled and tapped for mounting the leadscrew-nut, but as it's in-progress it's not worth putting them in as they'll be dis-assembled and re-assembled a good few times before the whole thing is done)


and from above;




And the rear central Z carriage with 2 guide-rods (2 are not strictly needed, but they turned out to be useful for holding bearings for guiding the belt) from below, showing the 2 Igus bearings (held in a blind pocket) and the leadscrew nut.


and from above;


You can see on that pic the "T" piece that links all 3 Z-axis carriages, and also you can see the present fixing arrangement (a M4 screw attaching it to the carriages thru a slot in the "T" piece). This is going to be changed as I have an idea to incorporate the bed levelling into this mounting.


This is a shot of the routing of the Z-axis belt around the rear central carriage leadscrew and guide-rods. I wanted to make sure that the belt had >90 degrees of contact on each of the pulleys driving the leadscrews, so you can see that the 2 guide-rods were very handy to pop a couple of bearings on to help "wrap" and guide the belt around the 40t pulley


A wider view showing the belt-tensioning device



And a close-up view of the Z stepper mount;




Here's a closer shot of how the belt routes around one of the front leadscrews and guide-rod;



The leadscrews are 2mm pitch, and they are driven by 40t pulleys, the Z stepper has a 20t pulley on it, which will give a full-step resolution of 0.005mm (more than I need, I may put a 40t pulley on the stepper)

One of the 3 leadscrews has virtually no runout/wobble, but the other 2 need some "adjustment" to get them closer to running true. It doesn't seem to wobble the whole carriage, but there is a slight, but noticeable, increase of resistance to the belt movement. So the plan is to take them out and then find out exactly where the bend is and attempt to straighten it out.


So next up is straightening out the 2 wobbly leadscrews, and then sorting out the bed-levelling arrangements and the mountings for the bed itself.

Stay tuned for the next update (but maybe don't hold your breath, LOL!!)

WeldingRod:
Important tip: take your leadscrews out and slide your carriage up and down by hand.  If it doesnt run free over the whole span, solve that first!!!

Sent from my SM-G892A using Tapatalk

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