Increasing Print Area

My Factory3D clone of a Prusa i3 has one irritating feature... the x-travel is insuffcient to cover the whole buildplate in the Y-direction, even with careful setting up.

Some 'crude engineering' today - basically cutting lengths of ground stainless rod and allthread to length and then replacing the Y-travel parts on the printer (like heavy duty Meccano).

My setup now actually places the home position just off the buildplate, a minor inconvenience when checking the z-height but a bonus as nozzle purges don't make a lump on the buildplate.

I do have to remember this when placing prints, but this is trivial as large prints have to be placed to avoid the bed clips (or the clips have to be moved to suit the print.) Anything small isn't affected.

Neil:

May I ask where you get your ground stainless rod, please?

I know what you mean ! I have the same printer !
Have you run a test at or near full capacity ? IIRC there are some X,Y,Z axis travel settings in the firmware (possibly to act as soft limits on the opposite end of each axis To where their respective limit switches are ?) Can’t 100% certain as it is a while back that i had to re load Marlin on my board . I know there are these settings in the slicer i use -Cura to stop one from trying to print something bigger than the build plate .

In Cura, I think you insert the maximum bed size and then it limits you, should you try to exceed those limits. I expect Neil will have simply inserted values for his table (if he uses Cura).

As a matter of interest, Neil, are you still using the version of Cura which came with the machine?

I have 14.12.1 and I seem to recall it was better than 'later versions'. However there seem to a number of major releases since then and, whilst the software seems to do everything I need, one feels left behind!

Iain

In the newest version of Cura you would choose the printer you have in the setup section and it will set the build table size automatically. With a little digging you will be able to find this setting and make changes to the build table size. Do so with care, prints will not come out like you intended if the print head or table hit the end of their movement as the stepper motors will chatter a bit and then assume they are at the right location while they are not.

Just searched for 8mm stainless ground rod online, seems to be a speciality of 3D printer cnc specialists. Our usual suppliers only seem to do drawn rod.

Neil

I'm on a much, much more recent version of Cura 4.6, the latest issue.

Before the mod the table stalled at max travel in each direction, I now have x=205mm, y=215.

Home is ~5mm off the bed in Y so that figure more or less centralises the print.

This part (photographed an hour ago) which is presently 5h 16m into an 8 1/2 hour print is 192mm diameter, so teh skirt is 202mm (and runs off the build plate at the front).

I'm curious about this since it was my (possibly quite wrong) belief that printers home the z-axis (after homing x and y using the limit switches) by reaching down and touching the build plate; then withdrawing a few steps and approaching slowly to confirm.

I don't see how it would do this if the x and Y homes are off the build plate. I presume it can be done, since you obviously have.

I don't see how it would do this if the x and Y homes are off the build plate. I presume it can be done, since you obviously have.

I’m sure mine comes down on the z axis until it hits the limit switch - the bed is levelled on that pisition, so it should make no odds where the home point is, in reality.

I don't see how it would do this if the x and Y homes are off the build plate. I presume it can be done, since you obviously have.

I’m sure mine comes down on the z axis until it hits the limit switch - the bed is levelled on that pisition, so it should make no odds where the home point is, in reality.

... er .... well .... so does mine now you come to mention it. I had this fixation that the z-axis worked differently to the others.

Put it down to age, addled brain and forced isolation.

No mine has a limit switch to one side, you set it to avoid the nozzle hitting the plate as the tips or build plate can be damaged.

That said, some printers have switch or capacitative sensors for automatic bed levelling, generally the contact type extends past the nozzle and retracts for printing.

Ah... just seen your second post!

Neil

Wouldn't you know it .... just when you're locked in and can't get out to the opticians.

I'll leave now.

Thanks. Just wondered if you had found a particularly helpful supplier.

Neil.

I too have the same printer as you, and won a few extra mm by putting a bigger piece of glass on the plate; you rarely print on the corners anyway it's mostly the skirt editing the machine bed size in Cura > Machine settings got the datum back onto the glass.

I wonder if you had any success printing PETG? I've tried many combinations of settings and get rubbish results, I've now got a bin full of scrap and lost my original cura settings for PLA... I can print the CV19 headbands in PLA but dismal failure in the preferred PETG... I tried two different rolls so don't think it's the material.

Thanks (in advance)
Mark

I wonder if you had any success printing PETG?

Isn’t it an accepted fact that flexible filament is difficult, or even impossible, to use with a bourdon type feed?

My Solvol, with a direct drive head, largely circumvents the issue of flexibility, I believe (not tried it yet as PLA is challenging enough for me at present🙂 ).

Hi Neil,

Finally done with all the current batch of collars, etc. Thoroughly overloaded on wildlife conflict stuff, so..back the the workshop and FINALLY back on my oddball 3D printer...

Starting with the Z axis, which first start with the table and how its constructed. Can you explain you table construction a little please? There ais a flat 'plate' under the actual print surface I presume - Aluminium? and then is that reddish material a silicone flat rubber heater? Is that flat up against the surface below it, and is there some sort of heat insulator between? The I presume the print surface is a glass sheet - right against the heater - what thickness is the glass? I see spring clips holding the sandwich together - how well does tha sandwich maintain its thickness, ie, is there not a possibility of the Z gap to print head varying with heat, and time - do you use print head leveling and do you do that everytime before printing?

Please..

Joe

Hi Joe,

If the bed moves as the y-axis then its mass needs to be minimised for optimum speed without inducing ghosting artefacts from vibrations on deceleration of the bed. As a compromise it is usual to have an aluminium bed of a few mm thickness (with attached silicone heater) which may not be stiff enough to hold its flatness. This is where auto bed levelling comes in, in my case with a probe lowered in place by a servo that operates an opto interrupter switch. If starting from scratch I would prefer a core x-y configuration with a more substantial bed only moving in z. In this case the better rigidity means that levelling is a one-off setup (for a fixed bed surface).

My preference for print surface is a PEI coated stainless steel sheet that attaches magnetically to the aluminium bed. This works without tricks for PETG and PLA. Prints can be easily released by flexing the plate. The plate can be swapped out for one with Kapton tape coating for printing ABS onto ABS slurry. Glass is also a very nice surface for printing ABS. Using auto bed levelling I can monitor the flatness and it is defined by the aluminium bed; the stainless sheet is pulled down flat to follow its profile to better than 0.05mm

Cheers,

Andrew.

Edited By Andrew Entwistle on 01/05/2020 10:00:08

I only carry out Auto Mesh bed levelling if I know I have disturbed the printer, but I do home in Z onto the print surface at the start of each print.

Some print beds have PCB track heaters, either clamped as a sandwich to glass, or bonded to the aluminium bed.

Edited By Andrew Entwistle on 01/05/2020 10:33:59