Another FDM printer

Martin Wynne

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To my surprise I've ordered another 3D printer. A second FDM printer to join the BIBO. This one, for £88 on Amazon:

https://www.amazon.co.uk/gp/product/B08V85TH34/

There are cheaper versions available on eBay, but see this note:

https://85a.uk/templot/club/index.php?threads/another-fdm-printer.340/post-3227

I want to see just what this tiny printer is capable of. And what changes I might need to make to the timbering bricks to be usable on it. 100mm x 100mm print area is very small, but now that I've got the brick connector clips working quite well, it should be feasible to create pointwork in 4mm scale in smaller bricks. It just takes a bit longer to do.

More importantly, the "kit" consists of just 2 bolts, and you are away:




So it's an affordable plug-and-play 3D printer for anyone who is wondering what this 3D printing business is all about, and how they might dip a toe in the water. Especially for the Plug Track bases and filing jigs, because for those you don't need any CAD system or CAD skills, the files from Templot are free and ready to print. They just need slicing, and the slicer software is free.

A video or online demo from me (or you) showing what to click next, and all that's needed to print a timbering base is Templot and a track plan.

It's not going to do the chairs of course, but for those there are several firms offering custom resin printing services.

All of which may fall flat when I get the thing, I'm hoping it won't be another disappointment like the Cameo cutter. As always the only way to find out is to get one -- trying to make a sensible judgement from the web sites is hopeless. But the video above is encouraging.

edit: The video above mentions the lack of a cooling fan. A fan now seems to be fitted to the latest machines, see:

https://85a.uk/templot/club/index.php?threads/another-fdm-printer.340/post-3227

cheers,

Martin.
 
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Hi Martin,
I wonder how many (young) kids will be getting one of these under the christmas tree ? It is amazing it prints so well ( relatively speaking ) straight out of the box. It will very interesting to see how you get on - I bet you can't resist making or adapting some add-on bits for it :)

Best of luck
Rob
 
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Martin Wynne

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Very interesting. My problem at the moment is lack of space to put new kit!

Nigel
@Nigel Brown

Hi Nigel,

It's smaller than it looks, the overall size is only about 8" square -- that's smaller than a sheet of A4 paper. And only about 9" high.

That means you don't need bench space for it -- it will fit on a bookshelf.

Even a short turnout in 4mm scale is going to need 3 bricks to make the timbering base. It's all easy to do with the brick connector clips which are already in Templot 232b, but there is quite a lot of clicking needed to set them up. I'm intending to add some functions to automate the process of adding clips to the basic turnout sizes.

If the thing works (which is still a big if until I've tried it), I'm hoping to get to the stage eventually where it's as easy to print a 3D timbering base from Templot as it is to print a paper template. A lot slower of course, but not much more difficult. Dream on. :)

cheers,

Martin.
 
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Hayfield

Member
Location
Essex
Martin

How easy is it to use for a numpty like myself Please

Secondly to the files available in Templot work without any other software adjustments with this cheap machine

The video was very helpful, in one way it perhaps shows that it might be time to buy one if not the time is very close
 
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Martin Wynne

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How easy is it to use for a numpty like myself Please
@Hayfield

Hi John,

At present I know nothing. :)

I'm expecting it to arrive today. It may not work at all. It may be brilliant. Online reviews vary between utter garbage and the best thing since sliced bread. Take your pick.

Secondly do the files available in Templot work without any other software adjustments with this cheap machine

If it works (remember this is still a big if) I shall provide whatever is needed in Templot to use it. You won't need any other software adjustments or skills, but there are two stages the files from Templot need to go through:

1. online mesh repair. (free). That's just a couple of clicks, you don't need to set anything. The links are already in Templot.

2. slicing. The machine includes its own simplified slicer software, but I expect to get good results it will be necessary to install the Cura slicer program (free), and set up some custom settings for the timbering bases from Templot.

Whatever is needed I will provide as simple clicks in Templot, and make a video showing what to do.

For some bog-standard turnout sizes, such as say a straight B-6 in 00-SF, I'm hoping to provide downloads of ready-to-use GCODE files for this printer. For which you wouldn't even need Templot, let alone any other software. Just download the file, copy it onto the SD card, bung it in the printer, switch on.

But remember 3 things:

1. it's small. 100mm x 100mm (4" x 4") maximum. Even an A-5 turnout in 4mm will need 3 bases clipped together (Templot can already do everything to create the clips). I shall need to do some smaller versions of the filing jigs to fit this printer.

2. there's no way it can do the chairs. They can be done on a home resin printer, or by sending the files from Templot to a custom 3D printing service.

3. IF it works. :)

cheers,

Martin.
 
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Martin Wynne

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Thanks, I will wait and see how you get on
@Hayfield

Hi John,

So far it looks promising -- all assembly screws are tight and the belts are properly tensioned (unlike the warnings on several web sites).

The Amazon driver looked exhausted -- unknown to me I made the mistake of ordering it on "Cyber Monday", and today was the day for all the deliveries.

I will write again when I have got it going.

cheers,

Martin.
 
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Hayfield

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Essex
But Cyber day was on Friday !!!

They will be busy for the next 3 weeks or more, but think of the overtime !!
 
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Martin Wynne

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But Cyber day was on Friday !!!
@Hayfield

Hi John,

I know nothing about all this, but Google says it was on Monday: :)

Cyber Monday is a marketing term for e-commerce transactions on the Monday after Thanksgiving in the United States. It was created by retailers to encourage people to shop online: Monday, 29 November 2021

cheers,

Martin.
 
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Hayfield

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I am getting it confused with black Friday, though it seems now to be a month long event. The Americans have a lot to answer for and I guess so have we for following it

How about a Templot Wednesday
 
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Martin Wynne

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To try it out I have perched it on top of the BIBO printer, so that I can use the spool holder on the back of the BIBO:

minibo1.jpg


So we now have BIGBO and MINIBO. :)

This picture does illustrate how much smaller this thing is than a regular FDM printer.

It's an odd thing to describe. At first sight the shiny orange plastic cries out "child's toy printer" and it is difficult to take it seriously. But then you notice some of the details -- all the fixing screws have threaded brass inserts in the mouldings; included in the box are little rubber feet for the control box; the user manual goes into technical detail far beyond anything a child would understand. In fact the first page of the manual says "keep the machine and all accessories out of reach of children".

Does it work? For starters I followed the instructions to the letter and it worked exactly as described. So that's the UK Sale of Goods Acts taken care of at least, assuming it is still doing the same in a months time.

Does it work for us? Well not surprisingly there are some things which need attention:

The X-axis bars are not exactly horizontal at 90 degrees to the Z axis. You can probably see in the picture that I have had to level the bed on a slant to compensate. For track timbering bases this hardly matters, and probably not for the filing jigs. But if you wanted to produce accurate fit-together parts it might matter a lot. I shall see if it can be squared up by dismantling and reassembling the Z head.

More significantly for us, the stepper motors have an integral gearbox to drive the belt pulleys. This means there is backlash in the axis drives which could seriously affect the accuracy of the timber and socket sizes. Also I suspect the gears will be the wear point which ultimately limits the life of the machine. The manual makes no mention of lubrication, but I shall be dismantling it and seeing what is required.

I was hoping the firmware might have a built-in correction to compensate for the backlash, but it seems not. However, I'm intending to write a utility to do that on the GCODE files, similar to the one I've done for the GRBL files for the CNC miller. If the backlash can be quantified, additional motor steps can be added or removed every time an axis reverses direction to compensate. Lots of trial and error to work through there.

There is also the possibility of correcting the backlash physically. There is minimal load on the X-Y drives while printing, so it would be possible to attach a cord to the table, and run it over a pulley to a falling weight. And the same for the extruder head. All a bit agricultural, but it might make a significant difference to the print accuracy. The Z-axis doesn't normally reverse while printing, so backlash there doesn't matter.

Also, the gearbox drives are very nearly non-reversible. This makes moving the unpowered drives by hand extremely stiff. As it's necessary to do that right at the start for the levelling process, it might easily put beginners off. There is no option on the control box to jog the drives under power. If beginners have failed to level the bed, it could explain the negative reviews on the web sites, especially if their X-axis is on a slant like mine.

But surprise, surprise, the box includes a USB cable and the software to allow the machine to be controlled remotely from the computer -- this is no toy after all. Which probably includes options to jog the drives under power, which would make levelling much easier to do. The instructions for setting up the USB connection are in the online manual, but not the printed version supplied in the box. I can't make much use of it without moving the MINIBO closer to the computer -- which in turn means making a holder for a full-weight filament spool. Lots still to do, but not worth spending time on until I've proved that it can print a usable timbering base. So that's next.

cheers,

Martin.
 
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Martin Wynne

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This is looking very promising.

I first tried a test print using the exactly same settings as the BIBO. With rubbish results -- badly warped, much stringing. Straight in the bin. :)

But after making some adjustments in the Cura slicer, it is looking very much better. In fact this is easily on a par with the BIBO results.

I'm using up some green PLA+ filament for testing, although the camera thinks it's blue. Today is the greyest day since records began, so it's a miracle it can see anything. This is straight off the printer (EM):

minibo2.jpg


I added the skirt to help avoid warping, which seems to have worked well. I removed the top surface ironing process, which just made a mess -- this extruder probably can't handle the fine flow adjustments needed. That means the top surface of the timbers has the usual mottled 3D-printed finish.

But after a light sanding with 320 grit (wet), and breaking away the skirt:

minibo3.jpg


which is as good as the BIBO. The camera is being cruel in close-up as usual. If it wasn't such a dismal damp day I might try a coat of primer on it (the print, not the camera :) ).

But the dimensions are all too small, even with the 1.5% shrinkage allowance, so I couldn't try any chairs in it. That's almost certainly the result of the backlash in the drives. So doing something about that is next on my list.

I set a print speed of 30mm/sec. The manual says 40mm/sec max, and it seems wise not to run it at the maximum for the best results. It could maybe go a bit faster. These 4 short timbers took about 45 minutes to print (unattended, no problems) for 2.67mm thickness, so perhaps an average of 12 minutes per timber on a typical turnout base. That means a typical turnout base will take several hours to print. Which isn't a problem if you plan ahead -- while building a B-6 turnout today, the machine can be chuntering away on the other side of the room printing a B-7 for tomorrow. :)

The time could be significantly reduced by printing thinner timbers (and chairs to suit), but then for Plug Track fitting the chairs with short plugs gets a lot more fiddly. Or maybe build the old-fashioned way on battens, so that the long plugs can project below the timbers? Or snip the bottom of the long plugs flush after assembly? Lots of ideas to try.

For some reason this machine rotates the job 180 degrees before printing it. Which doesn't matter in the least once you know about it, but it can be a bit confusing at first. In other words, although the Home position and limit switches are at the bottom left of the table, all the printing dimensions originate from the top right corner, and read backwards. I spent some time trying to fathom out what was going on and whether the steppers had been wired backwards. The answer is no, it works fine, just let it do its thing. Looking at some of the product photos, it's clear that no-one is quite sure which is the front of this machine, which may explain this strange way of working.

There are several online comments about the lack of a cooling fan on these machines for cooling the printed part. But this machine here certainly has a fan. You can see it running through the grille in the extruder housing, and feel the airflow around the nozzle. There is a slot and baffle directing the airflow down onto the work.

The X-axis started making some scrawnchy noises, but a little watch oil on the bars cured it completely. Cue lubrication all round, even though the manual doesn't mention it.

Now to get the dimensions correct, and print some timbers I can fit some chairs into ...

cheers,

Martin.
 
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Martin Wynne

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There are several online comments about the lack of a cooling fan on these machines for cooling the printed part. But this machine here certainly has a fan. You can see it running through the grille in the extruder housing, and feel the airflow around the nozzle. There is a slot and baffle directing the airflow down onto the work.
p.s.

Just checking that I'm not dreaming. The cooling fan seems to be a design change -- mentioned nowhere in the manual.

Grabbing a frame from the video I posted earlier, there was clearly an empty space behind the grille on that machine:

minibo_fan.jpg



Whereas on my machine the fan blades are clear to see:

minibo_fan1.jpg


Which is a round about way of suggesting that if anyone is thinking of getting one of these machines, it might be worth getting it from Amazon as I did:

https://www.amazon.co.uk/gp/product/B08V85TH34/

rather than one of the cheaper versions available on eBay and the far eastern web sites.

It is called WZTO Mini 3D Printer EasyThreed X1 which is far too much of a mouthful, so mine is now called "MINIBO". :)

cheers,

Martin.
 
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Martin Wynne

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Well this is a turn-up for the books. :)

I wrote a function to make some corrections in the G-code for the backlash in the drives. I was hoping it might improve the finished dimensions.

It's done a lot more than that. The print quality is much improved all round -- clean square edges, no flashing or stringing, and spot-on for dimensions. The chairs are a perfect press fit in the sockets with no cleaning up needed. I made no other changes to the file from the previous test piece, so the improvement can only be due to the backlash correction.

I'm loath to admit it, but this is actually much better than anything I have achieved on the BIBO.

Rather than sand the top surface, which tends to raise feathered edges on this toughened polymer, I think it might be preferable to scrape some filler into the timber tops to improve the 3D-printed surface. It's a lot better than before as it stands, and paint may be sufficient to hide the mottled effect. And there is still scope in the slicer to tweak the settings further.

Of course it is still a long way to go from 4 timbers in a test piece, to great swathes of clipped together timbering bricks, but it's a very promising start and much better than I expected from this little printer. Well done MINIBO. :)

As you have no doubt guessed, this means yet more buttons -- I hope someone is keeping count:

mbo_correction1.png


mbo_correction2.png


cheers,

Martin.
 
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Nigel Brown

Member
Location
Wales
Good stuff. Wondering how easy would it be to provide backlash correction to applications other than your track? I'm assuming it could be generally useful.

Nigel
 
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Martin Wynne

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@Nigel Brown

Hi Nigel,

Yes, it works on any G-code file for 3D printers, laser cutters, CNC engravers, lathes and millers, etc. But how much difference it makes on machines other than the MINIBO remains to be seen. Maybe not much.

There is a GCODE command M425 for backlash compensation, but not all machines support it.

At present my version has some limitations:

Only on 2 axes X and Y. It would be easy to add Z, and also possibly E for any retraction backlash in the extruder (but very difficult to measure).

edit: I have now added the Z-axis.

Only for absolute dimensioning. Relative dimensioning needs a different algorithm. (E often uses relative dimensioning).

Only for mm dimensions. It would be easy to add inches.

Only tested on files sliced in CURA. It should work with most other slicers.

But at present I don't want to get sidetracked into yet another project. It is mainly for low-cost 3D printers using toothed timing belts. CNC machines tend to use lead screws with an anti-backlash nut, so probably don't need it. Likewise more expensive printers using servos have backlash correction built-in. But having discovered how much effect it has on the MINIBO, I shall definitely be trying it on the BIBO.

cheers,

Martin.
 
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