FDM for Production  

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chocki
(@chocki)
Prominent Member

You can use dissolving supports for some complex models which need supporting from the inside, But I'm only using supports of the same material I am printing with, and only where needed, also if you look closely (You do need to check each layer using the layer view slider), you will see that the top support layer is approx 90 deg to the first supported layer (45 is better) this minimises the contact points between the two layers and makes it much easier to remove the supports, if both layers are running the same way, then the filaments will fuse along the whole touching lengths, if they are at an angle to each other, they will only fuse at point contacts where they cross over each other.

In the picture below, the green is the support material but is of the same material as the rest of the print and is only in contact on the one layer which would have been printed into fresh air, it does not touch the print in any other place, and since there are only crossing contacts, it is easy to remove with little surface scarring.

That slider to the right of the preview window is your best friend for successful printing, whether it is supports, or infill, and remember you have control over bridging angle and support angle, so don't just accept what slicer gives you, look closely where you get changes in layers and work out if it is possible to print what it suggests (Sometimes it tries to print top layers over voids which cannot hold the top layer!), and whether altering the infill pattern, density or amount of perimeters is better, again, sometimes printing walls, you are better off adding another perimeter rather than slicer trying to print a dot in mid air as infill!.

Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet....
Posted : 16/02/2020 11:13 pm
Paul McGarr
(@pmcgarr)
Eminent Member

@chocki

Thank you again for your help.  It is very much appreciated.  This makes perfect sense and it amazes me how scientific this process is when I (an SLA guy) thought FDM was primitive.  I find this interesting and can't wait to get my hands dirty.  I'm thinking I might be ready to place an order.  It seems reasonable to me that I can be successful given some trial and error.  I'm happy to invest the time learning.

Posted : 16/02/2020 11:20 pm
chocki
(@chocki)
Prominent Member

When you get your printer, post back on the forums and we can give you some tips for startup G Code tweaking which can give a better start with less dribbling resulting in a cleaner hot end and less possibility of burn bits falling into your prints.

Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet....
Posted : 17/02/2020 10:11 am
chocki
(@chocki)
Prominent Member

If your not planning on using the MMU, and going to plan to print with Polycarbonate or exotics later on, then look into a titanium non stepped heatbreak and nickel plated heater block from E3D and PT100 upgrade. No need to buy this lot now, but something to research.

Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet....
Posted : 17/02/2020 2:35 pm
Paul McGarr
(@pmcgarr)
Eminent Member

@chocki

Nice to know.  For now I plan to buy the mk3 with both print plates, a spool or two of prusa PETG and a .6mm nozzle.  That should cover it at least for getting started if I am not mistaken.

Should I buy the kit?  I'm a mechanical engineer so assembly should not be a concern.  But, I only want to do it myself if the experience is highly recommended.  I don't want to question if my inevitable printing issues are due to improper assembly by me.

Posted : 17/02/2020 2:48 pm
chocki
(@chocki)
Prominent Member

If your an engineer like myself, the build is well worth it yourself, but can be time consuming, I'm afraid pre-built is no guarantee of perfectly built.

One of these is worth getting for making sure your rods etc are aligned properly

https://www.amazon.co.uk/Eisco-Glass-Rectangular-Block-100mm/dp/B01BW05KVU/ref=sr_1_1?keywords=eisco+glass+block&qid=1581952110&sr=8-1

and I would recommend replacing the U bolts with something printed, but your going to need a printer for that first  🙂 

There was an excellent step by step guide for checking alignment etc of your printer which is where I got the tip for using the glass block from, I can't remember who wrote it, I think it may have been Guy2k or Bobstro, these two are very knowledgable, tim-m30 is always around to help as well as Joan and a whole load of other members.

Take a look at Bobstro's printer help pages: http://projects.ttlexceeded.com/3d_printing.html

 

Oh and lubrication, you MUST lubricate the bearings before use.

This post was modified 2 months ago by chocki
Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet....
Posted : 17/02/2020 3:22 pm
clemens.m
(@clemens-m)
Estimable Member

@pmcgarr

Assembly documentation is really good, assembly is done in a few hours and you learn a lot - to me it was also saving money as it is a hobby to me. The initial test of the printer after assembly will tell you if everything is ok - or where you have to rework the printer.

I again would by the kit,

best regards, Clemens Mödlin

Posted : 17/02/2020 3:23 pm
Neophyl
(@neophyl)
Honorable Member

I used the glass top of the halogen cooker as a basic flat plate to square my printer up.  Got a very low skew value when calibrated.  Assembly is not difficult but should take you more than a few hours.  Its best to take your time and check everything as you go along rather than rush it.  As already stated previously the build documentation is really and the online guide has tips/comments by people who have used it to give extra insight in places.

As well as the obvious cost savings self assembly also has the added advantage that you know how it all goes together so when maintenance is needed or for later upgrades its not a mystery.  

Posted : 17/02/2020 3:35 pm
Robert-mm200
(@robert-rmm200)
Noble Member

I would opt for the MK3S over the MK3, just because it is current production.

Your shopping list certainly sounds good. I have never seen a construction manual better than the Prusa.

Read it online - and read all the comments. They are a valuable part of the resource.

And take your time. The worst kit built problems seem to be from people who built it in one day - or less.

Like stated - grease your bearings when you get it. Heck of a lot easier than later teardown to do it.

Keep us posted on your progress.

Posted : 17/02/2020 6:06 pm
Paul McGarr
(@pmcgarr)
Eminent Member

@robert-rmm200

Thank you for pointing this out!  Yes, MK3S.  That's what I put in my cart.  I also decided to do the kit build.  I think it will serve me well because I like to know whats happening "inside" so I can understand things better.  Will keep you all posted.  You'll probably get sick of me because while I wait for the shipment I will be bumming around here, probably asking a lot of questions. 🙂

Posted : 17/02/2020 6:51 pm
Robert-mm200
(@robert-rmm200)
Noble Member

If (when) you have a problem that requires digging into the extruder - there is no better reference than that construction manual.

More pictures are available in the online version.

Consider E3D as an information source also. They have the checklist - and pictures - you really must follow on a nozzle change.

Posted : 17/02/2020 7:15 pm
chocki
(@chocki)
Prominent Member

Another tip with nozzles, especially if your going to go down the PETG route is use the nickel plated heater block and nickel plated nozzle combination and you don't need to carry out the hot retightening step since both have the same co-efficient of expansion, oh, and always carry out a cold pull before changing nozzles, it just makes life so much easier in the long run, no remaining filament to get stuck or get between the mating faces of the nozzle and heat break.

This is one of those tips you just don't see in the manual, but only takes a few minutes and helps prevent leaking filament when re-assembling.

Personally I do the following, firstly PLA probably gives the best cold pull, as PETG is just a bit too sticky.

The following two steps are only if you are not using PLA.

Purge any filament out with cleaning floss at the printing temperature of the filament.

Insert PLA filament until it starts to extrude.

Turn off the heat.

Slacken the filament drive to allow you to pull the filament out the top. (I have a skelestruder so no need to unscrew anything)

When the temperature drops just below 80 Degrees C, pull the filament out.

You should now have a clean nozzle and heat break and should be able to see light through the extruder, albeit a small light depending on your nozzle size 🙂

 

 

Something that hasn't been mentioned yet is, that you will probably need to reprint part of your extruder out of a higher temperature material very soon, as the part just above the heater block can and does soften and can droop until it touches the heater block, most people whom only print with PLA and the occasional PETG, wont see this issue, but if you regularly print closer to 300 Deg C, you will need to address this issue.

Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet....
Posted : 17/02/2020 7:37 pm
clemens.m
(@clemens-m)
Estimable Member

@chocki

What material do you recommend for that - Polycarbonat? Because that is the most resistante material to temperature I found (till now). Other suggestions?

Best regards, Clemens Mödlin

Posted : 17/02/2020 8:13 pm
chocki
(@chocki)
Prominent Member

Yes Polycarbonate, the purer the better. I used Rigid Ink clear PC as it was one of the purest polycarbonates available which meant it's glass transition temperature was the highest at 147 Deg C, there are other blends available, but these all have reduced Gt temperatures, not massively reduced, but still lower, but due to this they are easier to print.

I had to run my printer at the time to it's absolute limits to print the parts, but because they are relatively small parts, no heated enclosure was needed and I did not get any warping, I also printed some parts with more detail using a 0.25 mm nozzle.

Prints with this filament are like PETG on steroids is the best way I can describe it, ridiculously strong but with a hint of flex so they are not brittle.

Natural Polycarbonate is clear, so any coloured PC's will have additives, the more opaque, the more additives which could affect their final strength and or temperature resistance, hence why I went for clear PC, but you should be fine with any PC for probably anything you are going to print.

I'm just like that, rather than a it'll do version, I strive towards the best without going to the extreme or highest cost even though I could probably have done OK with  any PC filament.

 

I rebuilt the hot end last week to upgrade the printing temperature and a few other mods to be able to print this PC easier, unfortunately Rigid Ink no longer make filament, so I bought a few reels before they closed for good.

 

Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet....
Posted : 17/02/2020 9:07 pm
Paul McGarr
(@pmcgarr)
Eminent Member

Just placed an order.  Looks like I need to wait a couple weeks before it ships.  Thank you all for your help!

Posted : 19/02/2020 9:58 pm
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