Prusa i3 Build

[Enough!Participant @enough]

Posted by Neil Wyatt on 24/04/2017 08:41:55:

Funnily enough, I was thinking of using a feeler gauge.

I tried regular feeler blades at first but found they were a bit short in my case. Switching to the long Starrett ones was much better.

[BazyleParticipant @bazyle]

Norman, pity you didn't come along to the last Exeter DEMS meeting as someone was showing some pieces he had made. Brackets for something not the usual star wars figures and printed on a Prusa too. Someone else brought along a Stuart compound so we should have challenged him to make a printed one.

edit – looks like a printed D10 has already been done.

Edited By Bazyle on 24/04/2017 18:44:34

[NJHParticipant @njh]

Ah it's not the computer side of things that fazes me – I was in early – my introduction to them was writing simple Basic programs and submitting them on line to a computer bureau in New York! It all went on from there and computers have become firmly lodged in all aspects of life. I accept it all but I don't find it fun anymore – out in my workshop though twiddling handles and making swarf – now that IS fun. ( I do have a computer out there too – useful for reference but NOT connected to the machines. I want the fun of turning those handles myself!)

Norman

[Neil WyattModerator @neilwyatt]

Posted by NJH on 24/04/2017 18:17:54:

This makes me feel very old! – what will you use it for when it is made?

It doesn't replace the metal mangling, but it complements it.

It's incredibly easy to make useful bits and pieces, especially now I have sussed how to print usable threads.

I could do a list, but…

[Dave MartinParticipant @davemartin29320]

Posted by Neil Wyatt on 24/04/2017 21:50:58:

It doesn't replace the metal mangling, but it complements it.

It's incredibly easy to make useful bits and pieces, especially now I have sussed how to print usable threads.

I could do a list, but…

How about some of these Neil?

Dave

[Ian S CParticipant @iansc]

If you are buying acetone in bulk you may have to be careful, someone might start asking questions, I believe it is used in the manufacture of some kinds of illicit drugs. You might even have to sign for it, or be an approved company.

Ian S C

[Chris BaetensParticipant @chrisbaetens16442]

Posted by Ian S C on 25/04/2017 10:49:23:

If you are buying acetone in bulk you may have to be careful, someone might start asking questions, I believe it is used in the manufacture of some kinds of illicit drugs. You might even have to sign for it, or be an approved company.

Ian S C

Terrorists also use aceton if I'm not mistaken…

[Paul H 1Participant @paulh1]

Neil, can you reveal how you are modeling the threads please and what thread type? This is a subject that has come up on 3D printing forums and often causes difficulties. There are several people who have tackled this on Thingyverse with what looks like good results. Are you using one of these?

Paul

[Neil WyattModerator @neilwyatt]

Posted by Dave Martin on 25/04/2017 09:49:11:

How about some of these Neil?

Dave

That hoary chestnut!

3D printing lets you print those ready assembled

Neil

[Neil WyattModerator @neilwyatt]

Posted by Paul H 1 on 25/04/2017 13:19:39:

Neil, can you reveal how you are modeling the threads please and what thread type? This is a subject that has come up on 3D printing forums and often causes difficulties. There are several people who have tackled this on Thingyverse with what looks like good results. Are you using one of these?

Paul

I did it the simplest way possible in Turbocad:

Hollow cylinder at the outer diameter of the thread, centres at 0,0,0

Measured thread pitch at 1.7mm for two threads, so 0.85mm

Created an equilateral triangle 0.85mm on each side and placed it where I wanted the thread to be.

'Span' it into a torus centred on 0,0.

Changed properties so the spin had pitch 0.85mm and 10 turns clockwise.

Enlarged the spin by 0.4mm in diameter (on the second run after I found the original thread was too tight).

Placed the spin at the right z-height in the cylinder, duplicated it and put the copy at the other end.

Cropped both ends of the cylinder to length.

Saved as STL and printed at 0.15mm layer height.

0.2mm a side seems to be about right to allow for over-extrusion of the thread, its appearance is a two to three-layer continuous spiral.

It engages nicely (although it is easy to cross-thread) and seems to be more than strong enough for the light duty required.

I made an external 0.75mm thread for a t-mount adaptor the same way. I have done it up and undone several times and it doesn't seem to have degraded noticeably.

I think the secret is to accept that things like tip and root radii are meaningless at small pitches, and adjust the diameter to provide the required fit, using a 60-degree equilateral; triangle ensures that it will approximate to a metric thread, which is all you need.

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Chris Baetens on 25/04/2017 12:08:55:

Posted by Ian S C on 25/04/2017 10:49:23:

If you are buying acetone in bulk you may have to be careful, someone might start asking questions, I believe it is used in the manufacture of some kinds of illicit drugs. You might even have to sign for it, or be an approved company.

Ian S C

Terrorists also use aceton if I'm not mistaken…

Acetone is a commonly used solvent in organic chemistry and has a multitude of uses. It is also used as a solvent in other industries. One might just as well say that alcohol can be used in making drugs or explosives – or even water.

Here you can buy acetone in litre bottles in any supermarket.

Russell

[PETER ROACHParticipant @peterroach92938]

Neil

Thanks for documenting the Turbocad method. I made some "temporary" 22mm OD 9TPI buttress form nuts in 2013 in PLA. Being a lager thread got away with 0.3mm layer. I put a picture in an album. Needed to make another batch and forgotten the "revolve" and edit in the properties tree to make a spiral method. THKS.

Peter

[Graham ButcherParticipant @grahambutcher80356]

If you are looking for acetone try your local fibreglass supplier. For those of you from Essex there is one at Canvey Island. https://www.cybglassfibre.co.uk/shop/products/acetone

Hope this is of use

Graham

[ZebethyalParticipant @zebethyal]

Acetone can be bought in bulk from any fibreglass supplier, I recently bought 25l of 'Cure-it' acetone for when I re-covered one of my flat roofs with fibreglass.

[Paul H 1Participant @paulh1]

Neil, thank you for explaining your technique. Unfortunately this won't work for me as Turbocad is Windows/Mac and I use Linux. I would be very interested to know if anyone here has achieved the same result in FreeCad.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Paul H 1 on 28/04/2017 12:20:02:

Neil, thank you for explaining your technique. Unfortunately this won't work for me as Turbocad is Windows/Mac and I use Linux. I would be very interested to know if anyone here has achieved the same result in FreeCad.

Sorry I don't have time to check if this produces what you need but there are a number of Macro add-ons for FreeCAD. Screw-Maker, which I think is here, optionally generates real threads, though metric only. I find the option to produce a screw-tap, (i.e a length of studding) most useful. You can use them to make threaded holes using the Part Workbench to position the thread body in something else before subtracting it.

Despite having the excellent Fusion360 as well, I rather like FreeCAD and prefer it for modelling single parts. At the moment, FreeCAD's biggest shortcoming is the absence of an Assembly Workbench, which is a must have for many purposes. I hope they get one out soon.

Dave

[Neil WyattModerator @neilwyatt]

I must admit I am surprised that very few of 'our' suppliers sell 3D printers (Axminster do the Dremels).

Aside from selling to existing hobbyists it seems an ideal way of encouraging 'makers' to cross over into engineering.

Neil

[MWParticipant @mw27036]

I really liked the look of the prusa I3 and especially after having seen their recommendation in the magazine, I think this is having a knock-on effect, because I can't get hold of one.

I asked the guy who runs the site when a new one would be relisted and he said Wednesday evening, I didn't get paid till Thursday morning and it appeared as though he hadn't done it,

so I asked him again on Friday and he replied that they get sold so quickly you have to be within minutes of the listing to have a chance. So he said the only thing I could do would be to wait until next week to get another chance at bidding for one.

I politely refused so unfortunately I'm having to look at other models simply because of this supply problem.

It might be a bit of a moan but it just goes to show it doesn't matter how good the product is if I cant get hold of it!

In the end I've bought a sintron kit, so I guess i'll see what this is like and see it as a chance to review a different model. 

Michael W

Edited By Michael-w on 19/05/2017 11:53:57

[Neil WyattModerator @neilwyatt]

I think the problem is they print the PLA parts themselves, so they are probably listing them as soon as they get a complete set of parts!

Having some grief at the moment with PLA that just doesn't feed nicely, the biggest issue is that it is badly wound on the spool so somehow it gets slightly jammed, leading to small gaps in the printing. I have upped the current for the filament stepper which helps and has reduced this to a minor cosmetic issue (I was junking parts before solving the problem) but I am still having to keep an eye on the filament for potential jams – just cleared one. I'm doing an 18-hour part so this is a PITA, although its big enough and of a nature where I can stop the print, re slice with the bottom taken off and epoxy the parts together – I did this with the matching part as I suffered a broken thermistor wire, so the print stopped, followed by two more stops as the solder joint melted, then my crimp connection broke and I then eventually got a new thermistor. The part was in five pieces (the final stop was after it had branched into two parts). Fortunately the z-height is very accurate so a vernier reading of print height, then crop the bottom off gives two parts that match OK.

[MWParticipant @mw27036]

Posted by Neil Wyatt on 19/05/2017 12:07:37:

I think the problem is they print the PLA parts themselves, so they are probably listing them as soon as they get a complete set of parts!

Having some grief at the moment with PLA that just doesn't feed nicely, the biggest issue is that it is badly wound on the spool so somehow it gets slightly jammed, leading to small gaps in the printing.

Yeah I understand they're a small company and probably never anticipated so many people wanting this beefier version of the I3. I'll look on it as a means of adding diversity to our printer users!

That's unfortunate about the spooling inconsistency. Not really experienced in this field yet but could it be a temperature stability issue? The more heat might help the gooey plastic to lubricate it's way through the tubes.

I know that with injection moulded thermo-plastics which are a whole different animal but with those, when recycling nylon, you need a lot of heat and pressure to get it to shift.

Michael W

 

Edited By Michael-w on 19/05/2017 12:17:03

[MWParticipant @mw27036]

PS, might wanna check this out Neil, if the extruder feed is giving you trouble;

This is an upgraded version of the stepper extruder head used on the prusa I3, and although it is intended for the one I bought, they claim it can work with most reprap machines.

**LINK**

I paraphrase in sintrons own words;

"The extruder is the most important part of a 3d printer, and also the most difficult to calibrate, we have made necessary design to prevent "jammed" problem. I cant emphasize how important this is and other sellers don't have this and would cause many problems….

The MK8 extruder is open source universal suitable for most reprap and DIY long distance feeding filament 3D printers"

 

Michael W

 

Edited By Michael-w on 19/05/2017 13:07:41

[Rod AshtonParticipant @rodashton53132]

+ one for the Sintron. Transformed my old Mendel90 when coupled with an E3D head. As previous be cautious about too much retract, especially if running a Bowden tube (which was also a big improvement in the lightly built Mendel90). – No connection with either party, just a contented client.

[MWParticipant @mw27036]

Theres also some bowden tubing sold here if you do consider that head..

**LINK**

Or this one comes with the "hot end" head as well as a tube. 

http://www.ebay.co.uk/itm/Hotend-J-head-All-Metal-Bowden-extruder-For-Makerbot-Reprap-3D-printer-parts-/131807680763?var=&hash=item1eb05998fb:m:mXauTMFkUxY9tBYvJwbiBew

Michael W

Edited By Michael-w on 19/05/2017 14:29:35

[Colin HeseltineParticipant @colinheseltine48622]

Has anyone on here had a look at, or use, the Fisher Delta 3D printer. They were on a stand at the Doncaster show last weekend. The build quality looked good (to me) but it was not printing at the time.

Wondering how the Delta type of printer compares to the Prusa i3.

Thanks,

Colin

[jimmy bParticipant @jimmyb]

Posted by Colin Heseltine on 19/05/2017 14:46:35:

Has anyone on here had a look at, or use, the Fisher Delta 3D printer. They were on a stand at the Doncaster show last weekend. The build quality looked good (to me) but it was not printing at the time.

Wondering how the Delta type of printer compares to the Prusa i3.

Thanks,

Colin

I bought one at the Warwick show, last year. Been ok, but took some fetling. They are only as good as the build!

Not sure if I would buy the same again, ( it was £350). But the "delta" design is quite a good one.

Whatever you get, NEVER, NEVER buy cheap filament, use a trusted supplier…..

[Author]

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