Sunday, 4 December 2011

Frame Assembly

I now have enough parts to start on the frame.

Short work was made of cutting the lengths of studding by using the chop saw attachment for my angle grinder, worth every penny of whatever I paid for it at Aldi.


Having chopped the six 1m lengths according to the cutting regimen, I then proceeded to drill the various holes in the cast parts using my pillar drill (something that has paid for itself several times over, mine was from Wickes, current price is £65.00, pretty sure I paid no more than £45.00)


All was going very smoothly, indentations in the parts to start the drill in the right spot, until I put too much pressure on one of the Z axis motor mounts:


Still, all is not lost, after the application of some superglue to re-attach the broken pieces, I was able to finish drilling this piece, and unless you look very close, you cannot even see the join.

Having finished with the drilling, I started putting the frame together, the two sides were completed in hardly any time:


When I came to put the top bars on I discovered an issue with the parts: The hole drilling locations on the parts do not all actually line up! The Z axis motor mounts are supposed to slide on to the top bars, however the holes drilled in the top frame piece are too close together to allow this.

So off came the top bars, and top frame piece and the holes were suitably "adjusted" on the drill so that they were the right distance apart.

I had to leave out a couple of nuts and washers next to the Y axis motor mount, as the shafts on my motors are a bit on the short side.


I measured all of the vertices and all seem to be the correct lengths, however the frame will still not sit level. This is again probably an issue with slight differences in hole locations and differences in thickness of the various parts. I will worry about this some more when I have the smooth rails and I am ensuring that axes will travel smoothly.

Thursday, 1 December 2011

Parts start arriving

Well I have now amassed most of the items required.

My Clonedel parts from Metrix Create:Space turned up the day after I chased them, took just over a month to arrive, they are definitely colourful and some of them are designed in a slightly different manner to a printed set. Surface finish is a bit rough as the originals are produced on a powder printer before molds are taken.


I ended up buying 4 Pololu boards complete with heatsinks from Ebay at just under £7.00 each, instead of the StepStick boards I mentioned last time, these arrived in a couple of days from Denmark, costing £1.27 for postage.

I have just about collected all of the parts for my Sanguinololu, I just need to solder it all together, total cost of the board and associated electronics was £13.25. Parts for the opto endstops came to about £1.00 each for 6, making a grand total of £47.28 for all of the electronics, so well within my estimate of £50.00-60.00.


608-ZZ Bearings also from Ebay at £1.20 for 10, delivered next day.

My studding, nuts and washers order has arrived from Orbital Fasteners, 1m lengths of M8 BZP studding at £0.75 each, M8 nuts at £1.36 per 100, M8 form A flat washers at £0.59 per 100 (all inclusive of VAT), and because I live in the delivery area for their van and placed an order for over £20.00 worth of parts, next day delivery was free as well (I almost never just buy for the current project).

The stepper motors all came with a metal 16 tooth T2 gear attached which will be a shame to remove, so I am looking at alternative belt options, which will ultimately give me better print results anyway.


I can buy 5mm wide open length T5 belting from Belting Online for £2.25 per meter, which is the standard belt for use on a Prusa, but would prefer to buy the T2 belts to use with my stepper gears. Unfortunately the longest length they supply is 710mm (£6.27) and I potentially require 2 lengths of around 900mm, so would either need to buy one of these and a 200mm belt (£3.21) or a 600mm (£5.68) and a 280mm (£3.54), 292mm (£3.60) or 320mm (3.71) length to join together, so around £9.50 per 900mm belt (all prices are ex VAT). I may yet ask them if they can do me an open length of belt for a similar sort of price.

I am also moving towards the idea of a bowden extruder, as again I can make use of the already attached gear on the stepper motor squeezing the filament past a bearing. This method allows for less moving mass on the printbed, which allows for faster printing. The eMaker Huxley design already uses a Bowden cable from a modified Wades Geared Extruder.

I am currently thinking I will use something along the lines of the Wildseyed Simple Hot End, I am also thinking of utilising some pneumatic fittings at either end of the Bowden tube, they are pretty cheap £1.63 each for an all metal one, this should be an easy fit to the air hose fitting, used with this Hot End as they are both available with a 1/4 BSP thread, and then a length of 6mm PTFE tubing will be a simple push fit.

Current estimate for the total cost for this project is around £135.00.

I don't really subscribe to the idea that a RepRap should be capable of self replicating, and as far as I can see, certain areas of the project seem to be rapidly moving away from this ethos as well. Firstly, most of the electronics seem to be heading towards surface mount components, which are not exactly beginner hobbyist friendly, and good luck milling the pcb on your 3D printer. Second, until it is possible to print the various bar items, threaded or otherwise, nuts, stepper motors, etc the goal is a bit far fetched.

Choosing printable items over cheap vitamins is also often a false economy, yes you may be able to print a given part, but if the equivalent purchased part is cheaper than the cost of printing it - why bother?

I am all for reducing the parts count and think that the Printrbot variant has a good handle on this concept, one of these, or an eMaker Huxley, will probably be the first child of my Prusa.