Alone3 and SumPod Painting Part 2

Regardless of this success, I have yet to published any pictures from my SumPod painting sessions.  This post remedies this situation and I say sessions, because of the interruptions, some of which you can hopefully avoid with advice from my previous post:  Paint, Paint, Glorious Paint!

My primer of choice for intricate parts is Plasti-kote Primer Super, it's a solvent based primer that sticks to pretty much everything; multiple coats (including sanding) are possible in a matter of hours, with a touch dry time of twenty to thirty minutes.  Product details are available here.

It was not made clear in my previous post, that a solvent based primer should be used to minimise swelling of the MDF.  My thanks to Freyr for highlighting this important point in the comments.  The Safety Data Sheet for the Plastikote Super Primer is here.

Having read the comments on my previous post and the deterioration of weather here in the UK, I am revising my advice to use spray paint, unless you are lucky enough to live in a warmer and drier climate or have the facility to use spray paint indoors, then use a paint brush to apply primer.  Speaking to Richard (Mr SumPod), all of his demonstration units were painted using a paintbrush.

The following pictures were taken of prep during the last day or so of nice weather, that was the last of the British summer.

SumPod and newspaper ground protection bask in the British Sun

First picture of the 'exploded' SumPod as clouds gather

Main body, inside of left hand panel (upside down)

Main body, top of base

Main body, inside of back panel (upside down)

Main body, inside of right panel, with PCB cutting bed above

Main body top

Main body inside of front

 The LCD mounting space is clearly visible in the middle of the screen.

I will amend this post later with additional images from my other camera.

I started with the main body because this will have the most exposure to grubby fingers and 'stuff'.  After the first coat coverage is like this:

I'm paid a visit by Folly the thirteen year old fox terrier bitch, wondering what the hell I'm doing and not paying her attention.  Dogs can be sooo helpful.

Ideally the undercoat should consist of several thin layers of primer to provide the best base for the top coat.  Here yo can see the coverage of two (or three I can't remember) coats of spray primer.

Because the main body is held together by interference joints, moving it has caused this corner joint to loosen. Try to avoid getting and paint into these joints because it will make the joint even tighter and may create an unsightly gap.

A corner on the main body starts to separate

Z axis linear bearing mounts

It is clear how the routed surface of the MDF has soaked up the paint, compared to it 'normal' surface.  Speaking to Richard the soaking in is less of a problem with thicker brush applied primer.

My intention was to slowly build up the number of coats of primer.  Each subsequent layer is absorbed less and less buffered by the previous coat.  Following are pictures of later coats as painting and sanding progress:

Like it or not, the dual feeder backplate is not reversible

The first coat of gloss goes on as the night draws in.

The second and final coat of gloss will be applied tomorrow by brush as the weather here is currently less than conducive to painting outdoors.  Of the different finish options I've selected the slightly more difficult to apply liquid gloss - the finish should be fantastic!

Until then SumPod Guinea Pig signing off 

Paint, Paint, Glorious Paint!

The SumPod is painted.  Pictures will be posted later.  For the intended colour scheme of brilliant white, it was necessary to use a lot or primer.  A total of five coats over three days.  I recommend that everyone get fast drying primer and plenty of it, because you never know when it's going to rain, get windy, the light vanishes quicker than expected, you run out of paint or the inevitable and unforeseeable demands from family.  Save yourself the hassle, learn from my mistakes and avoid the pain in the posterior that is carrying wet painted parts through the house and the associated complaints about the smell.

As for specific quantities of paint, I was amazed at how much the edges of MDF sucked up paint - it just vanishes.  I used over a litre of primer, far more than I had originally anticipated.   Understandably I knew that a white colour scheme would require the thickest of bases to obliterate the colour of the MDF, but with no previous experience of spray painting MDF, I was surprised and ran out of paint on more than one occasion.  A darker colour would obviously require fewer coats, so you may only need two spray cans for your SumPod.

Get some sand or glass paper, three or four sheets should be enough.  I used coarser grit than the recommended 220, but even 120 grit provides a smooth if slightly scored finish between coats.  The trickiest part was smoothing the curves of the main body as the glasspaper had a tendancy to remove the paint from these surfaces first.  This was compounded by the amazing paint sucking abilities of MDF and goes some way to explaining why my SumPod required so many base coats.

I think the use of spray paint compared to applying the paint with a brush or roller helps improve the surface finish.  That's not to say brushing on the primer would not provide as good a finish, because it is only an undercoat, but I found that spray paint was very easy to use, provides good coverage, makes painting difficult to reach and complex areas (there are quite a few) pretty painless.  Overall I think the extra expense for the speed and ease of use to be worth the extra money.

I'll let you know when I finish the final coat (yes, I ran out of paint, again) if the coarser grit produces a smooth enough finish.  After all I don't need the SumPod to have the glass like finish of a coffin, it's a 3D printer.  The finish should look nice and the paint will afford the SumPod a degree of protection from grubby finger prints (perhaps white wasn't the best choice of colour), oil, splashes of stuff, moisture, small children and that most caustic of substances baby drool.

Until later SumPod Guinea Pig signing off.