Rapid Prototyping

[John Stevenson 1Participant @johnstevenson1]

Interesting point here in that I am interested in affordable 3D printing as a limited production exercise.

Recently been working with Art Fenerty of ex Mach3 fame on his gear program, Gearotic. Art has recently bought a printer the UP! Mini to print bevel gears to check his program. When I expressed an interest in one he said to wait as there are some good moves in the pipeline, it appears that two patents that are relevant to 3D printing expire next year.

However still keeping a look out and when a friend bought one of the Reprap Huxleys I popped down for a look. To be honest i wasn't impressed with the print quality at all, would not do what i wanted as regards quality so it went on the back burner again.

Last night I was up in St Helens sorting a machine out and popped in to another friend in the area [ yes I do have two friends ]

Just that day he'd bought a UP! mini off Ebay not working and a quick look found two dry joints and it was back up and running.

He'd printed a 20mm cube off and the quality was good but it was a bit out on size and slightly out diagonally.

In the software is a calibration file which consists of 4 l shaped towers at 90 degree to one another over a 100mm area and about 60mm high. The program said 1 hour and 20 minutes to print, when I left it has 12 minutes to go but it was getting really late.

Once it's printed the software asks you to measure across flats, across diagonals and measure if the towers are square. you enter all these figures into the program and it then calibrated the machine to the work table – dead neat.

However the point was the quality was spot on far better than the Huxley I had seen previously so I thought it might be down to operator not understanding the software ?

However today just got the latest MEW and in the article on the Reprap there are clear pictures of the print quality which being polite are crap, fuzzy edges, layers that seem to overlap a bit and stringy bits all over. Nothing like the print quality of the UP! Mini which I thought was very professional.

Anyone got a UP! Mini to sell ?

[jason udallParticipant @jasonudall57142]

John..I think UP! is the brand Cutwell are offering

[Gone AwayParticipant @goneaway]

Another variation: 3D DLP Printer

[Michael GilliganParticipant @michaelgilligan61133]

The "enthusiast" machines currently seem to be at the "proof of concept" stage … [compare; Fox Talbot in Photography, or the Wright Brothers in Aviation] … there is nothing wrong with that.

For engineering purposes; a component made by laying-down strings of PLS or ABS extrusion seems unlikely to have much future. [consumables are expensive, and structural integrity is questionable]

But: I would like to try extruding Wax, for the production of Lost-Wax Castings.

• Does any member of the forum have experience of this ?
• Are suitable nozzles available for RepRap machines ?
• Can we use a hopper of granules instead of a reel of filament ?

Grateful for any advice.

MichaelG.

.

Note:  Wax is cheap to buy.

Edited By Michael Gilligan on 05/08/2013 08:28:58

[Tony JeffreeParticipant @tonyjeffree56510]

Michael –

No particular reason in principle why you shouldn't use wax in a 3D printer. Sure, the feed mechanism would be different, but there are ways to fix that – for example, use a stick of wax and feed it into the nozzle in the same way that a glue gun feeds its glue stick, or force the wax down a tube using a plunger on a feedscrew. A hopper full of granules and an Archimedes screw feed would be a possibility – that is essentially how the plastic extruders that make the filament work. The challenges would be around accurately controlling the feed rate and the nozzle temperature; might also take some experimentation to get the right wax mix so that it stays put after extrusion but also properly adheres to the layer below.

[BazyleParticipant @bazyle]

'Surely' for anyone with a CNC mill all that is needed is a decent extruder head. Although the reprap bods like the idea that the print head is itself printed, again 'surely' a CNC cut version of all parts would up the game somewhat. Add to that borrowing the stepper off your 4th axis for the feed ought to make a trial printer no more than a few hours and pounds for material for a CNC operator.

Why isn't the above happening all over the place?

Edited By Bazyle on 06/08/2013 17:12:53

[Tony JeffreeParticipant @tonyjeffree56510]

Posted by Bazyle on 06/08/2013 17:12:02:

'Surely' for anyone with a CNC mill all that is needed is a decent extruder head. Although the reprap bods like the idea that the print head is itself printed, again 'surely' a CNC cut version of all parts would up the game somewhat. Add to that borrowing the stepper off your 4th axis for the feed ought to make a trial printer no more than a few hours and pounds for material for a CNC operator.

Why isn't the above happening all over the place?

Edited By Bazyle on 06/08/2013 17:12:53

Good question. No very good reason, except that some CNC mills might be a bit pedestrian speed-wise – with a machine that essentially has no cutting forces to deal with and where the head is very light, you would choose rather higher speeds for the axis movements than you would be used to on a CNC mill. Starting from a CNC router table would make perfect sense though – swap out the router for an extruder head, put a heated platter on the bed, and off you go. Funnily enough, I was chatting with John S just this morning and he was suggesting exactly that kind of approach…

Regards,

Tony

[jason udallParticipant @jasonudall57142]

As to wax on fused filament printing

.wax melt ..but does it have a “plastic” phase?
But pla filament is usually used with the big boy printers only for printing support. .its easier to remove from the abs part proper.
.pla is more brittle and be washed out with a hot solution of caustic soda…so this might lead to using pla as “lost” wax …
All in all this subject is still in its infancy. ..maybe after a couple of centuries this too will be finished like say turning…as to material..
There is printable woodfilament the colour changes with print temperature and thus growth rings can be printed….couple this with a dendrochronology database and you can print a part “felled” in any year you fancy….interesting times indeed

[Gone AwayParticipant @goneaway]

Posted by Bazyle on 06/08/2013 17:12:02:

Why isn't the above happening all over the place?

Perhaps because amateur CNC isn't quite as ubiquitous as it would sometimes seem. And of those, the owner would have to also be interested in 3D printing. Which rather narrows the field.

[jason udallParticipant @jasonudall57142]

Also Sid..the rapid prototyping thing has only “taken off” as part of the machine making parts to make machine ideology. ..the hobbyists 3d printing has grown out of a different philosophy. ..the software is critical to creating the object file and futher sw post process to make the g code file …
In any case the table top printer appeals to a different group of user than the by need hefty mill…but I can say I have seen extruders fitted as effectors to mills

[EnnechParticipant @ennech]

There is a place for 3D printing but there is a cut-off point in terms of object volume where is is cheaper to manufacture by CNC subtractive processes

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Tony Jeffree on 06/08/2013 16:48:38:

Michael –

No particular reason in principle why you shouldn't use wax in a 3D printer. Sure, the feed mechanism would be different, but there are ways to fix that – for example, use a stick of wax and feed it into the nozzle in the same way that a glue gun feeds its glue stick, or force the wax down a tube using a plunger on a feedscrew. A hopper full of granules and an Archimedes screw feed would be a possibility – that is essentially how the plastic extruders that make the filament work. The challenges would be around accurately controlling the feed rate and the nozzle temperature; might also take some experimentation to get the right wax mix so that it stays put after extrusion but also properly adheres to the layer below.

.

Thanks Tony

That's pretty much how I was thinking.

MichaelG.

[John Stevenson 1Participant @johnstevenson1]

Posted by Michael Gilligan on 05/08/2013 08:20:25:

The "enthusiast" machines currently seem to be at the "proof of concept" stage … [compare; Fox Talbot in Photography, or the Wright Brothers in Aviation] … there is nothing wrong with that.

I don't see this concept.

Basically they are a 3 axis CNC machine which enthusiasts have done very will over the years with a heated bed and heated nozzle added which are no more complex than the bought models.

If anything because these enthusiasts are working along different lines chances are someone is probably in advance of the smaller cheaper commercial units like the UP!

However when you compare quality there is no comparison.

My take on it is that engineering quality doesn't come into play in their designs in an attempt to get things working on a shoe string.

The Reprap for instance looks like a spider on crystal meths, if they had a semblance of engineering put into the design like a decent frame, supported rails etc they the part build quality would go up greatly.

As regards a place for 3D printing at present CNCZone has 7 forums dedicated to 3D printing with 2,402 posts. Add to this reprap, UP and other makes having their own forums and there is a lot of traffic.

Just because it not posted here or is in your face doesn't mean to say it doesn't exist.

[Gone AwayParticipant @goneaway]

Posted by John Stevenson on 06/08/2013 22:28:31:

…………….. if they had a semblance of engineering put into the design like a decent frame, supported rails etc they the part build quality would go up greatly.

 

Like this you mean?

Not quite on topic (but interesting anyway), the construction of this or this might be adaptable to a 3D printer.

Edited By Sid Herbage on 06/08/2013 23:17:02

[Michael GilliganParticipant @michaelgilligan61133]

John,

I don't think RepRap was ever intended to be a serious Engineering machine.

It is, as I said, a "proof of concept", and that concept is "self replicating machines" … as clealy stated in the manifesto on the RepRap wiki. [ yes I know it can actually only replicate the trivial bits of the machine ]

I agree 100% that, for our purposes, a modified CNC mill would be a better starting point, but we would also need to get away from the plastic filament …. which is why I asked about using Wax, with a view to using the output for Lost Wax Casting.

MichaelG.

.

Edit: This looks more like what I was considering.

Edited By Michael Gilligan on 07/08/2013 00:03:56

[John Stevenson 1Participant @johnstevenson1]

Michael,

With all due respect it depends on what you want to use one for. Why would you want to get away from the plastic filament if you wanted to make a plastic part..

Using wax is fine If you are wanting to do lost wax but how many users can visualise using lost wax and it's attendant casting procedures as opposed to making a plastic part ?

In the past couple of months I have recognised a need for various parts for the motor rewind industry that 3D printing is well sourced to do.

I recently had to mill a terminal block out from a block of Delrin which would have been far quicker and pleasing if it had been printed.

Also try milling this out of a block of Delrin

Standard fans are literally 10 a penny but get a weird one that needs a lead time of a day or less and it's well worth it

[Michael GilliganParticipant @michaelgilligan61133]

John,

Absolutely no argument with what you are doing … you are looking for something to reproduce a component which would originally have been moulded; and printing is an obvious choice.

For something closer to what I had in mind, please see the link in my Edit, above.

MichaelG.

[John Stevenson 1Participant @johnstevenson1]

Michael.

In an earlier conversation with Tony Jeffree yesterday now which he mentioned I have been doing some research of adding a heated bed and extruder head to an existing Isel router I have.

It's an old machine but very very repeatable, If I engrave a badge and tell the program to re run it will remove no further material which is a very crude but excellent test for repeatability on a CNC.

You will be surprised by how many so called professional routers cannot do this without double cutting.

Going along the reprap route, I need a bed, extruded head, the control board and software to make the conversion over from router to printer.

Rough costs are £44 for extruder head

£54 for electronics board including 4 drivers

£36 for the display electronics

£20 for the heated bed and add to this a few pounds for the bits I have forgotten, so probably about £175 in total.

What stops me at the moment is the Isel is a working and paying machine but it is limited by it's 300 mm x 300 mm footprint. It's on the cards to replace it with a larger 600 mm x 400 mm machine and once this is in and running them it takes the weight off the Isel so it can be converted

[Michael GilliganParticipant @michaelgilligan61133]

John,

Thanks for this … very interesting indeed.

For the sort of plastic components you describe; it is obviously the way to go.

However: My reason for asking about Wax is that I foresee the need to make small precision castings in metal. There is no specific job in hand, but I'm thinking of small "restoration" components: Items that would originally have been cast in Brass or Nickel Silver. … If the available technology permits me to build a suitable machine [or to adapt an existing one] at a reasonable price, then 3D printed Wax would suit my purpose nicely.

MichaelG.

[John Stevenson 1Participant @johnstevenson1]

I readily accept that we have different goals, most do but I feel the basis is to get a printer that will put out a decent job and then go on to experiment with materials knowing the machine is not a weak link.

Take that reprap that features in MEW, if you got this to print wax and got the results shown in the pictures then, at least for me, the quality would be useless for lost wax casting.

However how would you know what the culprit is ? At least going the filament route at first which is proved ground you can sort machine / heater / extruder problems out before taking a new challenge on with different materials.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by John Stevenson on 07/08/2013 08:36:04:

Take that reprap that features in MEW, if you got this to print wax and got the results shown in the pictures then, at least for me, the quality would be useless for lost wax casting.

.

Agreed

If I ever build my wax-machine, it's more likely to be based around an old Toolmaker's Microscope.

MichaelG.

[jason udallParticipant @jasonudall57142]

Is the finish”shown” a function of speed vs nozzle size. .machine resolution accuracy or slice thickness(read speed)..or is there a practicle limit to the filament (or rather extrusion) diameter..thus “grain” size…I have seen parts “polished” by dip / wash in acetone. .
No one has discussed the unbuildable objectds that can be printed with no assembly required or even possible. .have a trawl through thingy verse…
But yes few of the home build machines are sturdy vibration free machines we would desire. .John. .maybe selective sintering might be of interest. .dust box on your laser cutter..haven’t seen any experiments apart from in icing sugar.

[Trevor WrightParticipant @trevorwright62541]

Only one comment to make, my Huxley has a feed-rate of 12m/min, and it needs it. Reduce the feed-rate to CNC machine rates and it will be printing all day. Besides which the effort of printing oscillating strokes on a heavy bed will burn the drive motors out very quickly.

The Huxley has a print bed of 3mm aluminium plate, 160mm square and a cardboard and pla frog, the inertia is miniscule and allows the use of small stepper motors.

The Huxley print quality could do with improvement, but we deburr metal after cutting so what is wrong with fettling a 3d printed part? Most is caused by forcing the filament down a tube, when it does not need to extrude, the tension in the filament caused by being pushed releases and creates strings. But then again it only cost £450….

Trevor

Edited By Trevor Wright on 07/08/2013 13:02:41

[jason udallParticipant @jasonudall57142]

Trevor..At last some input from someone with experience of these beasts

[Russell EberhardtParticipant @russelleberhardt48058]

I must admit I have been put off building one of these things after seeing the print quality in the MEW article. Is that typical? Perhaps, Trevor, you could post some pics to show what print quality you acheive?

Russell.

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