Author Topic: Sheet Metal Brake and 3d Printer.  (Read 5898 times)

Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1130
  • Country: gb
  • Newcastle Upon Tyne
Re: Sheet Metal Brake and 3d Printer.
« Reply #25 on: September 06, 2018, 07:30:41 PM »
My problem is that the plastic snotters just don't suit what I/we do. Heck, maybe one day I'll just make one to win the argument...

I think that's my problem. Not that i'd be in a hurry to spend £5000 or whatever it is for a big ultimaker or a replicator or a duplicator or a binglebot, where all their budget seemed to go into getting some 'baby's first industrial design' shell made for it. But that I kinda wanted to prove a point in building my own machine but i'm still not entirely sure what that point was supposed to be. I guess just that I hate most of the designs out there for one reason or another and thought I could do better. But now i'm not so sure.

Actually i'm sure if I actually comitted to any of my shoddy designs they'd be better than a good chunk of the stuff out there, even commercially produced stuff with multiple thousand price tags.


I have 3 older Createbot Miniís.  The touch screen versions are not an improvement...  They really went to town getting the cost/quality down 8-(   Maybe they raised their game again, but looking at the review ratings I think not.  A couple of Mini Kossel printers, but they still out fox me with the complex setup every time you change the firmware, I will get the better of them. A now defunct Printrbot Metal Plus is the last on the list and being rebuilt with a newer 32bit Duet board and E3D hot end.  Some of the old printing posts mention the Mini printer.   Prior to all that I started out with a loaned Rostock Max 8bit delta.  If you wanted an excersie in frustration that was the printer to have, but I learnt a lot from that machine.

PK, I have just been lucky, right place, right time.  The people who have prints off me use them for presentation, brain storming or just to get an idea of what an injection moulded part will look and feel like in its application.  Only one client uses direct printed parts from me as end user parts, the setup cost for the intended mould was £10k plus and he can just call a print off as and when with modifications only needing CAD tweaks before the print.  We did test the end user acceptance to printed parts first and they had no problem, but itís a very bespoke product.

Looking at the rise and fall of several companies it seems to be that they all die when they decide to exchange a decent design for a scaled back design in some sort of Star Trek minifridge designed by people who only know bad videogames.

I had a good laugh at Solidoodle's goodbye message.

A few years ago Solidoodle was one of the leading manufacturers of consumer 3D printers, with 70 employees and over ten thousand units shipped. Regrettably, we stumbled on the launch of our 5th generation product, the Solidoodle Press, which fell short of our high standards for providing an outstanding consumer experience. This led to a downward spiral of declining sales and layoffs that further hindered our ability to deliver a great consumer experience.

Phrases like Consumer Experience are so insane to me, especially in this context. 

I guess it's a tricky market as the fad died out and the Chinese undercut everyone, but trying to trick people with a fancy exterior is just plain dishonest.



Also seems Windows installed but its refusing to activate for 'security reasons' and refusing to download updates. A restart might fix it but i'm done for today.

Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1130
  • Country: gb
  • Newcastle Upon Tyne
Re: Sheet Metal Brake and 3d Printer.
« Reply #26 on: September 06, 2018, 07:34:55 PM »
Had they arrived on schedule, we would have had much more time for testing and inspection, and would have realized crucial cash flow much sooner.

Seriously this corporate talk cracks me up. It's the way they can't shut it off when addressing the public, like they fully believe in this language and it's message. I wonder if there are any lawyers out there that talk legaleze in casual conversations.

Offline WeldingRod

  • Full Member
  • ***
  • Posts: 167
Re: Sheet Metal Brake and 3d Printer.
« Reply #27 on: September 06, 2018, 08:20:57 PM »
I've gotta chime in...
My exactly constrained design is a 15" class machine.  The Y axis is overhung from the main Z rails.  A key technique I used is having one thing controlling each degree of freedom.  As an example, the Y axis has wheels running in grooves on the left and wheels running on FLATS on the right.  That way, the alignment of the Y rails isnt important.
That said, I found that my Y 20mm square rails sagged more than a layer under load, but repeatably.  I used mesh leveling and totally solved it.
If you have a CNN and/or a plasma cutter, my design is easy to make.

Sent from my SAMSUNG-SM-G891A using Tapatalk


Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1130
  • Country: gb
  • Newcastle Upon Tyne
Re: Sheet Metal Brake and 3d Printer.
« Reply #28 on: September 07, 2018, 11:24:32 AM »
Finally got windows update to work. On the 32 bit version it just... worked. And installed everyting, graphics and audio drivers and all. But for some reason on the 64 bit version it took alot of searching and various tedious workarounds to get it to work, including reinstalling the operating system yet again.

I also had to reinstall it again after I somehow managed to set a password I couldn't re-enter. Guess my fingers were misaligned on the keyboard in some manner while I was half asleep.


I know all this has nothing to do with 3d printers, but I haven't had a chance today to even think about them. Reinstalling an operating system once is a bit of an adventure, but after 4 times it just becomes a little more hopeless feeling. I think when I get my PC back i'll start looking harder at whats actually on the market. There's stuff like the CR-10 I believe that retails for quite alot for a machine assembled from extruded profiles, but maybe it'll look more appealing if I actually price up assembling something similar. That said I don't care much for the whole Y axis on the table design that's quite popular. Having to move a changing mass and also taking up alot more desk space than neccecary for the movement.

Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1130
  • Country: gb
  • Newcastle Upon Tyne
Re: Sheet Metal Brake and 3d Printer.
« Reply #29 on: September 07, 2018, 12:04:22 PM »
Another look at gumtree and this has come up. And only this.

https://www.gumtree.com/p/printers-scanners/3d-printer-anycubic-kossel-pulley-assembled-with-auto-level-sensor-/1312934735

Not about to rush out to buy the first thing that appears, and i'm not super psyched about delta machines, but doing a quick read suggests its a RAMPS1.4 based thing. Which along with an arduino, 4 stepper controllers, and 4 of the cheapest motors on the one website I was looking at comes to just about £100. That'd also not be including a power supply or the whole extruder deal. Hot ends look easy enough to make with a lathe. So I guess that asking price isn't too riddiculous, but I still don't think it'd be Massive Savings over buying the parts. Especially since I don't think that machine itself looks very good.

Offline Joules

  • Hero Member
  • *****
  • Posts: 1029
  • Country: gb
Re: Sheet Metal Brake and 3d Printer.
« Reply #30 on: September 07, 2018, 12:08:12 PM »
Simon, cast your eye over this one at some point.

https://openbuilds.com/builds/core-xy-cube.3536/

Not keen on the wheels running on extrusion, but the cheap eBay rails could be a good substitute.  An interesting starter that could have a fabricated steel shell.

Look up some YouTube reviews for that before committing (Anycubic Kossel).  Build the hotend, buy the nozzles.
« Last Edit: September 07, 2018, 12:41:17 PM by Joules »
Just get doing and make swarf, you can decide what its going to be later.   :thumbup:

Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1130
  • Country: gb
  • Newcastle Upon Tyne
Re: Sheet Metal Brake and 3d Printer.
« Reply #31 on: September 07, 2018, 01:29:06 PM »
I had a look at those openbuild rails. They're an interesting idea but yeah I wasn't super psyched about them either. And not very competitive in price against other kinds of guides. Not for relatively short spans at least. Was considering making my own wheels and even ordered a few of the cheapest bearings I could find to try them out. They were incredibly tight and hard to turn.

There's a place nearby in stockton on tees, which isn't far from where I usually buy metal, called Valuframe that sells the regular aluminium profile. It's a good deal cheaper than the V slot stuff.





Also FINALLY. 64 bits this time.



That has to be the worst time i've ever had installing an operating system. I installed Windows98 on an old 90s laptop last year and that was fairly painless with easy to find drivers. I even ran pirated XP for years and that was so easy to install I was doing reformats twice a year just to keep the boot times fast.

Windows 7 used to be great...

Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1130
  • Country: gb
  • Newcastle Upon Tyne
Re: Sheet Metal Brake and 3d Printer.
« Reply #32 on: September 10, 2018, 01:33:15 AM »


I found this way tricker to produce than it should've been, since it's just a bolted box. Spent a while ditching folded sheet metal ideas until I was left with just extrusions. Not really figured the gantry out but there's plenty of coreXY stuff to look at to get ideas from.


Offline WeldingRod

  • Full Member
  • ***
  • Posts: 167
Re: Sheet Metal Brake and 3d Printer.
« Reply #33 on: September 10, 2018, 08:46:53 AM »
A good trick: drill through your extensions and tap the center hole.  Soooo much more rigid than the standard tinker toy bits.  Corner blocks with through bolts are better than angle bits also.  This is based on actual use/comparison, BTW.
Also, I suggest some double/triple wide beams on the bottom to get a rigid base.  If you do this, the top connections are much less ctitical.

Sent from my SAMSUNG-SM-G891A using Tapatalk


Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1130
  • Country: gb
  • Newcastle Upon Tyne
Re: Sheet Metal Brake and 3d Printer.
« Reply #34 on: September 10, 2018, 01:06:59 PM »
A good trick: drill through your extensions and tap the center hole.  Soooo much more rigid than the standard tinker toy bits.  Corner blocks with through bolts are better than angle bits also.  This is based on actual use/comparison, BTW.
Also, I suggest some double/triple wide beams on the bottom to get a rigid base.  If you do this, the top connections are much less ctitical.

Sent from my SAMSUNG-SM-G891A using Tapatalk

Thanks for the tip! I was looking at using the center hole just to save on hardware, but didn't know it was stronger!

Offline WeldingRod

  • Full Member
  • ***
  • Posts: 167
Re: Sheet Metal Brake and 3d Printer.
« Reply #35 on: September 10, 2018, 02:23:42 PM »
Since this thread is worthless without pictures, I dug some up!
You can see my base using triple wide extrusions in a kind of double-barred H; this lets me bolt through without having stuff intersect.  I use the side pocket for the power supply and brain.
One shot clearly shows the wheel-on-flat system I use on the far end of the Y and Z axis.  The idea is to only constrain one thing: rotation around the other extrusion.  Another shot shows the controlling Z and Y plates; these all run in the V-groove.

Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1130
  • Country: gb
  • Newcastle Upon Tyne
Re: Sheet Metal Brake and 3d Printer.
« Reply #36 on: September 11, 2018, 05:38:53 AM »
I appreciate the pictures. I also appreciate seeing a machine where the gantry moves up and down. It seems to be a rare arrangement for some reason.

I really like the look of the whole drive mechanism. Every time I look at coreXY and similar stuff it just seems overly complicated and prone to more problems than it'd solve (I get the feeling stuff like H bot and CoreXY is just trendy renaming of older plotter ideas). It's also interesting how you've refrained from joining the two vertically moving struts to make a box, but thinking about it - it does make more sense to do it that way and avoid over-constraining.

Is that machine a work in progress still or is it working?

Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1130
  • Country: gb
  • Newcastle Upon Tyne
Re: Sheet Metal Brake and 3d Printer.
« Reply #37 on: September 11, 2018, 06:37:03 AM »
Oh yeah a question i've been meaning to ask is 'whats the deal with PETg?'. From what I read a while ago it was spoken as if it was a wondermaterial. Strong as ABS but without the shrinkage and need for a heated chamber, and didn't seem too expensive either. But i'm still finding plenty of stuff that suggests people haven't given up on ABS despite that.

I do realise that for a large machine having a heated chamber would make things complicated. I've seen people struggling with cooling stepper motors but i've not heard much mention about thermal expansion, which I assume would cause issues. Especially if the whole thing heats up during the print.

Offline WeldingRod

  • Full Member
  • ***
  • Posts: 167
Re: Sheet Metal Brake and 3d Printer.
« Reply #38 on: September 12, 2018, 12:22:05 PM »
There are about a dozen of my bots out working, and mine has been banging out parts for years.  There's even instructions!

Sent from my SAMSUNG-SM-G891A using Tapatalk


Offline WeldingRod

  • Full Member
  • ***
  • Posts: 167
Re: Sheet Metal Brake and 3d Printer.
« Reply #39 on: September 12, 2018, 12:26:24 PM »
PETG is good stuff!  However, it doesn't glue worth a darn.  Pretty sure paint is out too.  You've got to make your part ready to use.
Just enclosing your printer improves all the thermal stuff a LOT.  That's what I do; waste heat from the bed is it.  I put the electronics at the air intake to keep them a bit cooler.  My old small printer used a light bulb and a dumb temperature switch to add a bit more heat.

Sent from my SAMSUNG-SM-G891A using Tapatalk


Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1130
  • Country: gb
  • Newcastle Upon Tyne
Re: Sheet Metal Brake and 3d Printer.
« Reply #40 on: September 12, 2018, 01:44:32 PM »
Aha that's good to know. Justifies the huge printer then!

Kind of a shame though since filler and paint was part of my plan to make some parts in the future. But from what i've heard of ABS it's a real chore for large parts.

Offline ddmckee54

  • Jr. Member
  • **
  • Posts: 85
  • Country: 00
Re: Sheet Metal Brake and 3d Printer.
« Reply #41 on: September 12, 2018, 02:35:25 PM »
Is there an accepted definition for a "Large" 3D printed part?  If so what is it?

Don
Too many irons, not enough fire.

Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1130
  • Country: gb
  • Newcastle Upon Tyne
Re: Sheet Metal Brake and 3d Printer.
« Reply #42 on: September 12, 2018, 02:46:43 PM »
Is there an accepted definition for a "Large" 3D printed part?  If so what is it?

Don

I don't think so, and it's part of the problem I had trying to find stuff to look at just going through google. Those huge novelty 3d printers and bogus grant projects suck up alot of the attention and search results.

Offline WeldingRod

  • Full Member
  • ***
  • Posts: 167
Re: Sheet Metal Brake and 3d Printer.
« Reply #43 on: September 12, 2018, 03:42:37 PM »
I'd classify "large" parts as bigger than about 6" in the longest dimension.

As for finishing large parts, it's a function of "how pretty" and "how often".  If you make an acetone vapor unit for your largest part, then you can make a big improvement quickly.  I've done that on parts up to about 6" tall; I printed a riser tube for my rice cooker and covered it with Aluminum foil tape.  There is a special epoxy resin for filling the grooves, but I haven't tried it yet.  The attached photo has a cat hole about 8" tall, mostly finished to fully smooth with a file.  Each side was probably an hour worth of filing.

Sent from my SAMSUNG-SM-G891A using Tapatalk


Offline nrml

  • Full Member
  • ***
  • Posts: 214
  • Country: gb
Re: Sheet Metal Brake and 3d Printer.
« Reply #44 on: September 13, 2018, 04:11:42 PM »
Another look at gumtree and this has come up. And only this.

https://www.gumtree.com/p/printers-scanners/3d-printer-anycubic-kossel-pulley-assembled-with-auto-level-sensor-/1312934735

Not about to rush out to buy the first thing that appears, and i'm not super psyched about delta machines, but doing a quick read suggests its a RAMPS1.4 based thing. Which along with an arduino, 4 stepper controllers, and 4 of the cheapest motors on the one website I was looking at comes to just about £100. That'd also not be including a power supply or the whole extruder deal. Hot ends look easy enough to make with a lathe. So I guess that asking price isn't too riddiculous, but I still don't think it'd be Massive Savings over buying the parts. Especially since I don't think that machine itself looks very good.

I have a half built Anycubic Kossel - linear rail version. I have swapped the hotend for a genuine E3D V6, the 12V power supply for  24V, the bed heater for a 240V SSR controlled unit and the control board for a duet (old version - not the wifi one). A lot of these parts were gathered over the years for various other projects and are being re-purposed.

It doesn't ooze quality but like most cheap Chinese kits if you upgrade the parts and assembly process judiciously, they can turn out quite good. I love watching delta and Corexy assemblies move. I find them very elegant in comparison to Cartesian assemblies, so I couldn't resist when I saw them being sold for less than £200 delivered last christmas.

Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1130
  • Country: gb
  • Newcastle Upon Tyne
Re: Sheet Metal Brake and 3d Printer.
« Reply #45 on: September 14, 2018, 05:17:19 PM »
Been putting this off because I just can't settle on a design.



Went back to CoreXY since it fit into what i'd already come up with the easiest. It's a little over-built though using the 40mm extrusions. I can't help but overbuild the wrong parts. It's often said that any idiot can make anything work, but it takes a real engineer to make something that barely works. I might use 30mm extrusions in the end.

I really like the look of your machine WeldingRod, and it's clearly a superior design to what I can come up with. But i'm not sure how you'd enclose it without making its footprint huge. The area I want to fit the machine is about 600x600, and id like the build volume to be at least 350x350x500.


So assuming I continue with this design then... where would be the best place to put the Z axis screws?



In the middle seems most obvious, but I can see it tipping as the gantry moves past the center point. But at the ends seems like there'd be alot of leverage to flex stuff...

Offline WeldingRod

  • Full Member
  • ***
  • Posts: 167
Re: Sheet Metal Brake and 3d Printer.
« Reply #46 on: September 14, 2018, 05:47:49 PM »
Fully enclosed, my printer is 690x690x660 deep for a 380mm build cube.  Yeah, it's pretty big! 

Sent from my SAMSUNG-SM-G891A using Tapatalk


Offline WeldingRod

  • Full Member
  • ***
  • Posts: 167
Re: Sheet Metal Brake and 3d Printer.
« Reply #47 on: September 14, 2018, 05:52:38 PM »
I would make choices to minimize and balance loads.  Your 3d model with the screws has good locations. 
Btw, speaking from having two screws... I highly recommend coupling them with a belt (if posdible), even if you have steppers for each.  When the power is off they can get desynchronized and tilt your z axis.  Also, watch out for backdriving the z when the power is off.  I use multiple constant force springs to counterbalance my z carriage and make it so it doesn't backdrive when it's off.  Belting helps this too, as you have to turn multiple motors to get in trouble vs only one.

Sent from my SAMSUNG-SM-G891A using Tapatalk


Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1130
  • Country: gb
  • Newcastle Upon Tyne
Re: Sheet Metal Brake and 3d Printer.
« Reply #48 on: September 14, 2018, 08:13:49 PM »
Coupling them at the bottom would be fairly simple I think, under the table. I figure it'd be a good idea to put the pulleys between bearings so it doesn't flex the screw.

Thinking about it some more, i'm going to be using cold rolled steel for the verticals. Ground rods are too expensive and at that point i'd probably do better with Chinese MGN guides. I sorta wonder how the bearings sticking would affect stuff. Maybe i'm blowing the problem out of proportion but i'm just imagining if I put the screws in the middle then the whole thing is going to be see-sawing about. I guess if that happens then I could add some struts under the table to add some more. 8 bearings! Overconstrained isn't a word i'm familiar with.


A bit ago I tried using autodesk inventor since it has alot of neat seeming features. Especially the kinematics and the deflection modelling stuff. Turns out the kinematics don't work too well for complicated mechanisms like straight-line linkages. And I find the method of modelling stuff really hard to get used to. Maybe it's a learning thing but I feel with sketchup it's really easy to move stuff about to brute force my away into a design, when with Real cad then you need a good idea of where youre going to begin with. But then I can't actually simulate deflections.

Maybe I should learn some maths.

Offline WeldingRod

  • Full Member
  • ***
  • Posts: 167
Re: Sheet Metal Brake and 3d Printer.
« Reply #49 on: September 15, 2018, 02:22:00 PM »
Exactly constrained means that a moving part on a machine has parts that locate it in X, Y, Z, Theta, Rho, and Phi.  Over constrained means that one or more of the directions and rotations have two or more parts fighting to control them. 

A common example of this is an axis running on two linear bearings.  To make this simple, I'll talk through it in terms of two ground rods with a total of four tubular linear bearings running on them and a lead screw.  Lets say X is the direction parallel to the rods.  The X direction is controlled by the lead screw; easy.  The Y and Z directions are controlled by the linear bearings.  Rotation around the X axis is controlled by the linear bearings, as are rotations around the Y and Z axes. 

There are two big over-constraints.  The first is that the pair of linear bearings on a ground rod MUST be co-axial to be able to move.  This is typically pretty easy to do, as you can often stick them on the rod and then screw them in place.  A lot of linear bearings include some facility to  provide a small rotation to self-align.

The tough one is the two ground rods.  If they are not parallel, then the motion will jam.  Getting them onto a common mounting plane helps alignment a lot, but you still have to get the two parallel (within the flex/slop of the system) to get motion to work.  We often solve this by using a flat surface to mount the ground rod ends and then doing the trick where you go to one end, tighten the mounts some, go to the other end and tighten a bit, rinse and repeat...

As for the rotations, lets think about X first.  If the table rotates around the lead screw, nothing happens (other than a little motion).  Thus, the lead screw doesn't control this rotation.  If we consider the right hand ground rod to be the master one, we can imagine rotating the table around it.  This rotation is prevented by the TWO bearings on the other ground rod; this means that its over-constrained, and that we have to do some sort of special alignment to get it to work.  Y and Z have an even higher degree of over-constraint; they each have 2 or 3 extra bearings fighting for control plus the lead screw is going to  resist rotation around Y and Z (and bind up).

If you go to a total of three linear bushings, things get quite a  bit happier.  Think of "three points define a plane".  Using a fork/slot bearing as the singleton is the best choice, or putting the singleton linear bearing IN a tight slot.  One or both bearings on a common shaft need a spherical housing (ideally something you can clamp after installation).  In a perfect system, the coupling between the lead screw and the table would have a couple of flexures so that the nut can seek its own happy spot.  Set up this way, X is only controlled by the lead screw.  Rotation about X is controlled ONLY by the fork bearing.
Y is controlled by the bearing pair (remember the fork is pointed in the Y direction).  Rotation around Y is also controlled by the bearing pair; the fork won't contribute any significant rotation resistance as its short relative to the pair.  Finally, Z is set by the three table bearings.  Rotation around Z is just like Y; the bearing pair.

After I funded the Cobblebot printer, I found out the hard way that they TOTALLY didn't understand this stuff.  They had a quadruple bearing group running in grooves on EACH of the four posts.  Thus, the darn posts had to be totally parallel for the Z to move at all!  And, the two screws had to parallel also.  Further, the motors were on the bottom, so the most critical position (starting) was the one most likely to bind up!  The Y axis had two bearing quads.  Again, requiring two linear rails to be perfectly parallel to each other.  X was the only one that would run reliably.

Sorry for the long blather!  Its a topic dear to my heart, and one that I spent a LOT of time on to get my printer working right.