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Prusa i3 3D printer

tekkydave

By tekkydave
in DIY Astronomer

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tekkydave

tekkydave

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I've decided to forge ahead with upgrading my 5mm z-axis threaded rods to 8mm lead screws. I've printed the plastic parts required using This Thingiverse item. I flipped all the parts to keep the x-axis rods in front of the z-axis keeping my current printer configuration. I also modified the x idler to use the x-belt tensioner arrangement I currently use.

The other parts required are on order:

Leadscrews (300mm)

5mm to 8mm flexible couplers

KP08 8mm bearings

prusa_lead-screw-upgrade01.jpg

 

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Gina

Gina

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Hope you will have enough stepper motor power with those multi-start threads :)  Guess it depends on the lubrication.  Oh and the weight of your X axis.  Guess it should be alright as they're sold for 3D printers.

Should have a lot less friction with a square thread form rather than a triangular one :)

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tekkydave

tekkydave

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I hadn't really considered it. Plenty of people are using them in Prusas and I haven't seen any negative comments about motor power. If it's an issue I could upgrade the z motors. They each have their own Pololu driver now so hopefully it will be ok.

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Stub Mandrel

Stub Mandrel

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The positive side is, while I've still got the Dremel, I'm printing a whole load of parts for the project. There are two door latches to keep the handle in place, I've printed two levers with square shanks and holes for a cord, another twist knob will fit over the cord so you just turn it and the latches will unlatch.

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Bagnaj97

Bagnaj97

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I bought myself a Hictop Prusa i3 clone and put it together over the weekend. It's my first 3d printer but I did a fair bit of research before taking the plunge - lead screws, aluminium frame, heated bed, auto leveling and a good size build volume are what decided it in the end. I was pleasantly surprised at not having to solder or crimp anything either - just putting plugs in the right places!

Has anyone tried printing tube rings? I've gained an ST80 but it was OTA only and I have no rings...

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Stub Mandrel

Stub Mandrel

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12 hours ago, Bagnaj97 said:

Has anyone tried printing tube rings? I've gained an ST80 but it was OTA only and I have no rings...

Printing a half-ring right now, for a Jessops 76mm newt I rescued from a mate's skip. 119mm diameter

I'm using a 1kg reel with the dremel and the feed route is poor and though the first part went OK but second print fouled up. Hope next three go OK at three hours each.

Should be fine for a light scope.

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Dave_D

Dave_D

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Just now, Gina said:

You mean you didn't buy filament for when you were ready to try your printer???!! :eek:

unfortunately, i have a major inflamation of the 'financially embarrassed' gland... took me 5 months to save up for the printer :/

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Bagnaj97

Bagnaj97

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The printer's been busy today. Now I need to buy an ED80 to sit next to the ST80, roll on payday...

The second bottom half is currently printing. I've discovered that ABS is horrible for prints this size, it really wants to warp. Masking tape and abs juice mostly works, but near the end of the print it's pulling the masking tape off the bed. I'm not sure PLA is durable enough for this (I don't store it anywhere warm, but might do some solar observing so it'll be sat in the heat). Has anyone printed in PETG? It's meant to have the durability of ABS but it's easier to print and doesn't stink - my concern is that it's more flexible and I don't want flexure - just how flexible/rigid is it?

For testing I balanced the bottom piece and hung 3kg off either end (from the bolt holes) without the top in place and it was fine. Given that the actual load will be nearer the centre, the top will be in place to brace it and there will be the second pair of rings I've got absolutely no concerns about it not taking the weight of the scopes - I could almost certainly make it less chunky, but chunky and strong reduces the chance of flexure.

Total weight of 2 top pieces, 2 bottom pieces, the handle and all the nuts and bolts is 509g, dovetail and any hex-thumbscrew adapters will be on top.

I need to print some M6 hex thumbscrew thingies now. I did a test one to make sure I've got the internal dimensions correct (grey in second pic) but need to give it something to grip - a smooth cylinder isn't great.

STLs and Sketchup files will go up on Thingiverse, but I've only just signed up and there's a 24hr block before new users can publish on there. It should appear here - http://www.thingiverse.com/thing:2116466

IMG_20170216_231252.jpgIMG_20170216_230641.jpg

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tekkydave

tekkydave

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All the parts for the lead screw upgrade have now arrived. I started by removing the KP08 bearings from their pillow blocks. To do this you need to put a rod or large screwdriver shaft in the centre hole and turn the bearing around an axis perpendicular to the face. It should then slide out through the slot in the mount.

Next I pushed the bearings into the holes in the upper mountings.

prusa_lead-screw-upgrade02.jpg

prusa_lead-screw-upgrade03.jpg

Next step was to put some M3 knurled nuts into the x-axis pieces using a soldering iron to heat them.

prusa_lead-screw-upgrade04.jpg

prusa_lead-screw-upgrade06.jpg

I then started fitting the brass inserts into these from the other side. I realised at this point that the x-idler part was missing a recess for part of the nut and the hole diameter was too small. Drilling out the hole was easy but the recess would have been an issue so I decided to modify the model and reprint.

There is a fixed version Here but I've already made a lot of mods to my version so I'll edit that and print a new one.

More pics later when I've reprinted....

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tekkydave

tekkydave

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It took me all pm to get the print started.

First problem was that Cura stopped working on my Ubuntu following upgrade to 16.10. I created a Virtualbox VM with 16.04LTS then installed Cura 2.4.0. Now I could slice the updated part.

Be aware if you are planning to use Cura on Linux the current stable (2.3.x) and beta (2.4.0) versions only work on Ubuntu 16.04 or less.

Next problem was printer was extruding way too much filament and just creating a mess. After some head-scratching I realised the x-axis wasn't level putting the nozzle at a slight angle to the bed. Once I fixed that it started printing ok. It has about an hour to go atm.

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