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"GinaRep Concorde" 3D Printer

Gina

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This 3D printer makes a bit of a departure from my others in that it is designed to give the best accuracy I can achieve rather than concentrating on speed or size, though I did want to print at least as big as my Titan printer (290mm x 290mm x 250mm).  Like Titan it uses a box as the main frame but unlike Titan and my other printers does NOT use "pink string and ceiling wax".  It uses tried and tested 3D printer designs rather than my usual "way out" ideas.  I took advice from a friend who has spent a lot of time on developing high accuracy 3D printers.



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This part of the CAD model shows the LH Y rail and rear support bracket plus Y carriage and X rail.  I think the Y rail will want to be shorter to allow for the motor at the front (unless the motor goes outside the box).

727134537_Screenshotfrom2019-01-1011-28-30.png.5f2d4676e1150f602d1947f1d02e27f3.png

 

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Gina

Posted (edited)

Printed the new Z carriage then added the V groove wheels with eccentric spacers in the larger holes so that any slack can be taken up.  Set it up on a V groove rail and adjusted out the slack then I tested for possible wobble and couldn't find any at all.  I think these Z carriages are going to work well but we'll see.

Here's a photo of the eccentric spacer used to take the slack out.

1762663897_Screenshotfrom2019-01-1020-52-44.png.f682631e0c33673f9574e0cc84999d28.png

Edited by Gina

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The bed frame is 500mm square on the outside so the slots are 480mm apart (500 - (2 x 10)).  Inside of box = 610mm so the frame wants holding at (610-480)/2 = 65mm - Tick...

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Some time ago I decided my Titan printer wasn't working as well as I wanted and at that time planned on replacing it with a new printer.  I bought a set of timing belts and pulleys for CoreXY drive plus three single start trapezoidal threaded rods 500mm long.  Then I found a way of improving the Titan and I abandoned the rebuild.  Now things have come full-circle and I want the threaded rods, they've vanished!  OK so they're somewhere on this property but...  I have a stop-gap though.  At one stage I tried using 4 threaded rods on my Giant printer (one in each corner) with timing belt drive from one stepper motor.  It wasn't successful so I tried with two motors but that was no better.  In the end I gave up on the 4 threaded rod system for my Giant printer.  This means I have 4 x 1m long threaded rods doing nothing ATM.  I could take one and cut it in half to provide the two 500mm rods I want for Concorde.

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Aluminium plate and glass plate added to bed frame.  (The blue bits are foam protection for the glass during transport and will be removed.)  The whole bed will be held together with a 3D printed frame.  It will be arranged that the frame can be taken off and glass plate plus print removed from the printer for faster cooling.  Also, the glass plate can be exchanged for another so another print can start before the first has cooled and detached from glass plate.

880353431_Build02.JPG.e4b75f0243164251b6323c90fcb4ed55.JPG

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Gina

Posted (edited)

In lining up the belts, pulleys and motors, I found a little problem which will entail a redesign of the Y carriages and rear pulley blocks.  Nothing serious - just a small delay while I change the designs and print new parts.  The problem is that the timing belt must clear the wheel spacers where it runs behind the Y carriages and means the pulley axles must be further from the rail.

Wheel spacers are 10mm OD, belt is 6.35mm wide and pulleys are 8mm wide, so the pulleys want spacing more than 5mm clear of the wheel axes.

Edited by Gina

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32 minutes ago, Stub Mandrel said:

Toughened glass or borosilicate glass?

It's actually ordinary float glass - I'm told this is quite adequate but if it breaks I'll have to think again.  I shall stay well clear while it's heating up!

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Designed and printed a basic X carriage front plate to check out where things will go.  Below is a photo with the parts roughly laid out on the plate.  Still to go in is the air duct for part cooling.

1303752649_XCarriage01.JPG.de0a5342d2e16cf5e584b80e2df4e26b.JPG

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New design for X carriage front with bracket for Z probe and slot for part cooler air duct.  Part cooler fan will be behind extruder motor.  The ridges match the grooves in the timing belt and provide positive clamping of the timing belt with a clamp plate and two screws.

606432078_Screenshotfrom2019-01-1214-08-39.png.d74b0758671662429ca7d8d42135867b.png

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Both Y rails installed, both Y carriages and all the pulleys.  XY motor brackets printed and next will be to mount a couple of motors.  Then I can work out the Y travel range and position of nozzle in the Y direction and hence the best position for the Z rails front to back. 

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Photo of current build state including XY motors with brackets.  (Not the best photo I'm afraid.)

136549138_Build03.JPG.c84681e0def689f993da9ebf2ffa290f.JPG

Edited by Gina

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I can now calculate the best position for the Z rails so that the centre of the printing area is in the centre of the bed.  I have measured the Y range as 450mm.  Better than expected.

  1. With the E3D Titan extruder the nozzle is 13.5mm in front of the base of the extruder ie. front of X carriage.
  2. X rail is 20mm wide so mid point to front is 10mm.
  3. 1mm gap and X carriage is 5mm thick giving a total of 10+1+5+13.5 = 29.5mm.
  4. Y carriages are 75mm wide and rear pulley blocks are 30mm.  Thus furthest back the nozzle will go is 30+75/2+29.5 = 30+37.5+29.5 = 97mm from the inside back of the box.
  5. Y range = 450mm so centre of bed wants to be 97+450/2 = 97+225 = 322mm from inside back of box.  OR on the outside of the box (easier to measure and drill), 322+18mm(thickness of ply) = 340mm.  I shall make up a template for this to ensure that the Z rails are exactly vertical.
Edited by Gina

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Z rails screwed in place and Z carriages attached to bed frame.

1965362521_Build04.JPG.163dd637d477b52acf13a36e3ba49498.JPG

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Spool holder bolted onto base.  The reel of filament fits under the bed and doesn't take up any usable space.  Filament will be fed to the extruder in PTFE (Teflon) tube.

1443472544_Build06.JPG.4d45cfa3da45bcc5de2eb7c1a37664fc.JPG1418562478_Build05.JPG.08ae9a04d1aca8f236f29a2b2cdc633e.JPG

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Currently printing the X carriage.  Been trying to think what sort of connectors to use for the interchangeable hotends.  My Giant printer uses Molex connectors as used in computers for DVD drives etc. but I'm not happy that these are good for this application.  For the Concorde I need 2 pins rated at about 3A for the heater and low current 2 pins for the thermistor.  The connectors need to withstand the vibration of printing and I would like the sockets to be fixed to the X carriage.  I'm now considering small spade connectors  but am open to suggestions.  Other ideas would be much appreciated.

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Gina

Posted (edited)

As I continue to build the new Concorde printer I'm running out of 3D printer spare parts and now "borrowing" parts from my Giant printer whilst retaining operational Mini and Titan printers until the last minute.  I shall need two of the more powerful stepper motors from the Titan to drive the Z drive rods, I think.  I plan to keep the Mini printer for the time being as it works fairly well for small parts up to about 200mm square.  I shall probably use the ready-made cables from the Giant printer to get the Concorde working and replace cables with the right length ones once it's working.  This means I can run the new cables tidily as I go along.  I have a new 2.85mm hotend and the extruder from the Giant on the new Concorde X carriage and the 1.75mm hotend from the Titan will provide an alternative interchangeable hotend.  As all the extruders are the same, so are interchangeable, the Titan one will probably go on the Giant later.

Edited by Gina

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X Carriage with extruder and hotend plus Z probe.  I have left the cover off the extruder to show the inner parts.

1372363382_XCarriage03.JPG.e9848bc79fd4ccbdd4f8f4f21957589d.JPG

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