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109jb
11-27-2016, 07:28 PM
I have a CNC milling machine and am looking at getting an extruder and hot bed to try 3D printing on it and had a couple questions.

1. For printing PLA, what kind of XY feed rates are required? I have 2 machines and the one I would like to experiment with has max feed rates of 35 inches per minute on all axes. I can use the other one if needed, but the slower one is in the basement as opposed to in the barn. Is 35 IPM fast enough?

2. I'm already running an Arduino Mega 2560, and can wire the machine up as if it was using a ramps board. What software is easy for a beginner to 3D printing. I have been looking at Repetier/Repetier Host. Is this one a good one for a newbie to 3D printing.

Thanks

John B.

underthetire
11-27-2016, 08:39 PM
Any speed will work, but that is really slow, I usually run about 3000mm /min on my printer. That software is fine for starting out, it's just slicing software, so once you get a good print /speed/layer/ temp it's almost set and forget. I ended up buying simplify 3d after using the free ones for a while, just better options in it.

Sent from my A3-A20FHD using Tapatalk

dharmic
11-27-2016, 09:53 PM
1. FWIW my printer prints infill at nearly 300ipm. The slower perimeters are laid down at around 130ipm. 35ipm will be cut-your-wrists slow and, because everything gets such a long time from one layer to the next to cool down, you're going to encounter issues of warping, parts lifting from the bed, crappy inter-layer adhesion and the like. Printers are designed to be fast with a light payload and next to zero force on the head, where as mills/routers are designed to carry some weight and cope with tool force.

2. I use Repetier Host on my machine (a Rostock Max delta from SeeMeCNC), and drive it using MatterControl. I find that MatterControl has a nice balance of not too many settings to get confused by vs enough to get a decent print, it's pretty easy to use and fairly reliable. It also lets you choose slicer between their own one and a couple of others (slic3r and cura) - generally if one doesn't quite get a particular part right then one of the others does. MatterControl is open source, being very actively maintained and their support channel is very responsive if you get stuck.

109jb
11-28-2016, 10:43 AM
Thanks guys. I figured that the one machine would be too slow. I guess it will have to go on the other machine in my barn that is capable of 200 IPM feed rates. This is really just a test to see if I like 3D printing. If I do I will build a dedicated machine for 3D printing, similar to the cube type machines. Am I correct that the Z axis feed can be pretty slow since it is only moving very short distances at a time for each layer?

Thanks again.

dharmic
11-28-2016, 05:05 PM
Yeah, the Z doesn't have to be fast - it's only moving .004" at the end of each layer and they don't typically do coordinated xyz moves.

That said, if you enable Z liftoff as part of the filament retract when jumping from one part of the print to the next, a slow Z will seriously increase print times.

To be honest I'd be more inclined to find a 2ndhand printer on eBay or the like, play with it and, if you don't like it, just turn it around again.

the_real_skimmy
01-14-2018, 04:52 PM
If your hardware can do 40mm/s with like 1000mm/s^2 acceleration, you are good to go.

A_Camera
01-16-2018, 03:47 AM
Thanks guys. I figured that the one machine would be too slow. I guess it will have to go on the other machine in my barn that is capable of 200 IPM feed rates. This is really just a test to see if I like 3D printing. If I do I will build a dedicated machine for 3D printing, similar to the cube type machines. Am I correct that the Z axis feed can be pretty slow since it is only moving very short distances at a time for each layer?

Thanks again.

I had a similar idea but even though my CNC is about twice as fast I ended up NOT using it as a 3D printer and decided to buy a cheap acrylic Prusa clone. I bought it just to test and see if I like 3D printing or not, knowing that it has a lot of limitations and weaknesses, but also knowing that if I like it I will be able to improve it and that I will also build a dedicated, high quality printer. Now a few months after I bought it I am ready with the improvements, learned a lot and also began building my own design.

I was advised against combining a CNC with a 3D printer for several reasons. One was that the mass of things is just overkill and will eventually literally kill my CNC because of all the very fast and small moves. The other was noise. Because of all the ball screws, a CNC is much noisier than than a belt driven 3D printer. Also, a 3D printer does not need the same mass as a CNC, so it is a pretty simple thing to build and it is a pity to "degrade" a CNC into a 3D printer, even if in my case it would have been a converted combo. Anyway, I think I made the right decision, the modified acrylic 3D printer is excellent and is extremely fast now after my modifications (15m/min on X and Y and 9m/min on Z) so it is very much usable for many things. So far I have only printed PLA but it is soon time to test other filaments as well.

How about you? did you end up modifying your CNC or bought a dedicated printer or nothing at all?...

BTW, I guess you know this already, but a fast Z is necessary if you need to lift and move the nozzle for during printing.