increasing build dimensions

[Joseph Helmstetter Jr]

On a mendelmax 1.5+, if I want to increase the bed to approximately 12 X 12 inches, would I only have to increase the bed size itself and the X and y components? Are is there something else I need to change too?

[Larry Knopp]

Increasing X only doesn't affect other dimensions; only widens the X extrusions and smooth rods.

Increasing Y, however, requires also lengthening the upright extrusions proportionally (Longer Y extrusions move the top extrusions further apart...)

Google around a bit...  there is a MendelMax scaling document around somewhere (I forget where Mike has it hosted, off the top of my head)

On Sat, Aug 23, 2014 at 1:10 PM, Joseph Helmstetter Jr <jhelmst...@gmail.com> wrote:

On a mendelmax 1.5+, if I want to increase the bed to approximately 12 X 12 inches, would I only have to increase the bed size itself and the X and y components?  Are is there something else I need to change too?

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[Alex]

http://www.mendelmax.com/wiki/scaling-mendelmax/

Once I find the original bom I can give you my dimensions for the extrusions.  It really works out to be 12+" x 16+" by 16"(z)?  hard to say with z because of bed and extruder hitting the vertex.

[Alex]

It looks like I added 100mm to everything

Original

4		HFS5-2020-300
4		HFS5-2020-340
6		HFS5-2020-420

Mine

HFS5-2020-400

HFS5-2020-520

HFS5-2020-520

[Michael Anton]

That's exactly the size I built.  I also increased the Y rods and the Z rods to 10mm from 8mm.  If I did it again, I would probably go to 12mm on the Y and increase X to 10mm.  It is worthwhile getting a bunch of the aluminum brackets from Misumi, and putting them everywhere you can to make the frame stiffer.

Mike

[Joseph Helmstetter Jr]

So I understand the increase in the extrusions but what size do you make the print bed? Obviously it must be at least 12 x 12 but is there any reason to add a border? I saw a bed heater that is 300mm square. 12" is right around 305mm so I am sure that would be perfect. I am also planning on using some linear rails and blocks that I already have from an old cnc route for the bed travel. The lead screws I have are acme 1/2" 10tpi. I believe that those would be good good the z axis. I will have to scale some of the existing parts but that won't be a problem. Is it worth using a remote extruder like on a delta or should I stick with Wade's style? Thanks for all the help.

[Michael Anton]

My bed is still the standard 214x214mm bed, as I haven't bothered to make a larger one.  In theory, on my printer, I could have a bed as large as 330mmx380mm but I probably couldn't print right to the edges.  But, mine is not a standard printer, and I have made many changes from the original design, so it all depends on how you set up the Y axis bearings.  The distance between the bearings in Y, will limit the max travel in that axis.

This printer was not purchased as a kit, and I sourced all of the components myself, though I did by the plastic parts as a kit, so I could get it running.  I designed and printed many of the parts I used, once I had my printer working initially.  This is not an exact representation of how it is currently put together, but it is pretty close.

If you have any other questions or want more details on my design, or why I did things the way I did, just ask away.  Someday I should get busy and publish all of the parts I designed, but I don't consider it fully finished at this point, as it will probably always be a work in progress.  There always seems to be more that can be optimized.  At the moment, I'm in need of redoing the extruder, as I purchased some gearhead steppers to replace the current geared Wade's extruder, which has been acting up as of late.  I figure at this point I probably have close to 1000 hours on it, so it is probably about time that it started acting up.

Mike

[Michael Anton]

On Wednesday, August 27, 2014 1:41:05 PM UTC-6, Joseph Helmstetter Jr wrote:

So I understand the increase in the extrusions but what size do you make the print bed? Obviously it must be at least 12 x 12 but is there any reason to add a border? I saw a bed heater that is 300mm square. 12" is right around 305mm so I am sure that would be perfect. I am also planning on using some linear rails and blocks that I already have from an old cnc route for the bed travel. The lead screws I have are acme 1/2" 10tpi. I believe that those would be good good the z axis. I will have to scale some of the existing parts but that won't be a problem. Is it worth using a remote extruder like on a delta or should I stick with Wade's style? Thanks for all the help.

If your leadscrews wobble at all you are going to trouble with Z banding, and will have a hard time removing it since the leadscrews are so large (unless you figure out how to decouple them from the X ends).  Even with my straight trapezoidal leadscrews, I had problems, though it didn't show up as the typical Z wobble.  Instead, it showed up as a thickening and thinning of the layer height caused by the screw wobbling in the loose nuts leading to a Z height change that was dependant on screw rotation.

If this is your first printer, I would suggest sticking with the Wade's extruder, as it will probably be easier to get tuned initially.  You can always move to a bowden style later if you want to.  I've been using 3mm filament, which some people seem to think is not a good idea due to the drag on the axis, but I can say that I haven't really had any problems using it.

Mike

[Urkijca]

Mike,

I'm new to this Group and also to 3D printing.  Apologies in advance is I'm deviating from some protocol or etiquette... 

I'm interested in building a 3D printer from a kit, but would like one axis to be longer than most standard envelopes.  I've looked around and it seems that if you only want to scale up one axis, it should be pretty straightforward.  I'm considering a Mendelmax 3 kit, which has a build envelope of 250x315x197mm.  I'd like to extend the 315mm to 380mm (or more if that's also possible... to a maximum of 455mm).    That's extending it by about 2.5" (or 5.5" for my extreme case).  How easy difficult would that be?

Are there other options to achieve this larger build envelope - I'm open to less expensive options as well... - if they exist. 

Thanks in advance for your thoughts. 

Best,

Carlos

[Michael Anton]

Hi Carlos,

 

Sorry, but I'm not that familiar with the MendelMax 3, since I built a MendelMax V1.5.  Generally, it is possible to extend the axes, depending on how the printer is constructed.  You may run into difficulties if it has a heated bed, as you will have to come up with an alternative heater for the larger bed.  Sometimes they are available, sometimes not, just depending on the size you settle on.

All I can suggest, is to do lots of research.  There is a pretty steep learning curve to using this technology, but it is pretty amazing once you get it all figured out.

Bear in mind that 3D printing is a pretty slow process, and the larger the build volume you want to print the more reliable your printer must be in order to be able to complete it.

Good luck,

Mike

[Urkijca]

Mike,

Thanks so much for the prompt reply.  I'll do the research.  Thanks for pointing me in the direction of heater bed.  

As to reliability, what are some of the things I should look for?  Frame stiffness, type of components, software?  I assume yes to all of those, but any more than others (how would I prioritize)?  I'll do the research on that as well.  

As to speed, I'm not worried (yet?).  I'm sure that will change with time...

Thanks again.  

Carlos

[Michael Anton]

Wiring on moving axes is a big failure point.  It is preferable to use wire that is rated for continuous flexing (though you have to pay attention to the bend radius rating), rather than standard PVC jacketed wire.  McMaster Carr has some nice silicone jacketed ribbon cable that I've found works very well.

Make sure the heater and thermistor are well fastened into the hot end, and can't shake loose (this can cause a fire if either of them happen).  Don't use a cheap hot end, as cheap ones will often jam mid print.  Running these machines unattended can be quite dangerous, and have been known to cause fires.  I'm not trying to scare you, but this is something to be aware of, so the machine gets treated with the appropriate respect.

Mike

[Larry Knopp]

I'll jump in w/ a couple of other bits to consider...

When increasing an axis size, you should absolutely look into up-sizing the smooth-rods as well.  "Standard" is 8mm dia., going to 10mm (I've even seen 12mm) will go a long way to reducing possible flex as you go larger.

And this is the biggest point about up-sized FDM (plastic extrusion) 3D printers that most folks don't take into account.

The larger a print job, the more difficult it becomes.  Exponentially so.  Very large prints will give you a hell of a time dealing with cooling, splitting, layer separation, and adhesion.  I won't go into the various ways to attempt to combat these issues, but just be aware of it (again, do some research on large prints...)

Asking the question, "Is it *really* necessary to go to a big print area?" is a really good idea.  Are the things you intend to make 100% needful of being that large?  You might be better served to design your things to be assembled from a few smaller parts that can fit comfortably on a "standard" sized printer.  The pains introduced by "going big" could very well turn the whole experience into an expensive, unsuccessful, frustrating nightmare.

My 2c...

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[Michael Anton]

All good suggestions.

I enlarged the rod diameter when I expanded the axes of my MendelMax V1.5.  I increased the dimensions by 100mm, so I increased the rod diameter on Y and Z to 10mm.  I left the X alone, and in retrospect I should have made it 10mm, and the Y at 12mm would have been better.  It is surprising how much flex there is in those rods.

I always planned to put a 300x300mm bed on mine, but I ended up with a standard 200x200mm bed that came with my electronics kit.  It's been a couple of years now, and I'm still using it.  It is only the very odd occasion when I wish the bed was a bit bigger.

Mike