Beginning a build

Good afternoon!

I started off by ordering lots of parts from here there and everywhere to get a system together. Sense then took hold and I ended up ordering a full electronics set from the RRRF store.

I soldered the whole set and did the first tests on the stepper motor boards in roughly 10 hours (over several days in between other work). I hadn't ordered any stepper motors by that stage but I took a look at the forums and decided it would be best to start off by building a repstrap using the 2nd gen electronics to allow me to print the parts to make the reprap.

I'm looking at assembling the parts for several of them and will be mainly sticking to the McWire Strapper. I'm going to make a few changes to the materials I use as some are either not available in the UK or are unusually expensive.

My first decision was to use 3/4" abs for the piping that forms the base and arm on which the system is built. I found that equivalent parts are available for most of the other items needed for the build.

If necessary, I will also fill the abs frame to give it more weight. Until I receive the material (hopefully later today), I will not know whether this will be necessary.

I'll add updates when I've anything else useful to add and will include links to sites as I find them (I'll confirm whether they're actually suitable before posting them here!)

I've enjoyed reading your experiences and hope to see many more people continuing to post. I've found the project to be good fun so far!

Right! I received the parts and obtained the final part I was looking for the following day so I now have all the parts needed to build the piping structure that will form the base.

I ended up ordering several sets of the materials required to make this part of the setup. Looking at the frame, I'm fairly sure that it will need some reinforcement to ensure dimensional stability (I think the 12" upright may flex slightly under the weight of it's load. Below you can see an image of the parts and a test assembly of the structure.





I plan to solve the possible flexing by filling the base with cement and placing a metal rod within the upright surrounded by cement. This will prevent flexing and will increase the weight of the structure to prevent movement during printing.

Next step is to cut and prepare some of the metal rails and ensure that the metal frame is square. I'll post updates when I have them

The cement sounds like a pretty sensible idea. Better hope you got that column vertical though... it might be a bit of a pig to adjust later

I've thought of that! I'm going to be fixing it with cement after I've done a dry run of the assembly. I don't want to risk having to go back to square one with this

A sensible time to do it would be after the metal framework is complete and assembled. That way, I'll have flat surfaces that I can check the level of in three planes before committing with the cement.

Right, I've made some progress in collecting a lot of the parts that are required. I'll put up details of all of the sources for the parts once I've got to a stage where I'm comfortable that the build is working.

I'm currently cutting the parts for the aluminium runners which will allow me to assemble the frames on which the stages will run. I'm making one change which is to replace the 1/4" 20 threaded rod with M6 threaded rod. The difference is a fraction of a millimeter in diameter. Obviously, I will also have to change the nuts and use M6 nuts instead.

I'll update again soon (hopefully with some new pictures!

A link that will be useful regardless:

[www.kateskates.co.uk] - I sourced the bearings here - 14.50 GBP for a set of 16. No shipping or handling charges for shipment within the UK.

Direct link to the ABEC 7 set I purchased here - [www.kateskates.co.uk]

I've assembled the ABS frame now and had several "hitches" with my plan to simply pour cement into the pipes to provide extra weight and stability.

Assembly of the frame was quite frantic. I chose non threaded tube and ABS adhesive. This adhesive bonds the joints very quickly which means that you'll have to be very fast to make any adjustments to the final position before it sets!

Before assembling the frame, I drilled the holes to mount the x rails on the base. I used the templates but must have twisted them on the surface of the rod as I went leaving one hole on each piece off of the center line.

I took this into account when drilling the holes in the rail and adjusted positions to fit. I also used a square to make sure that the rails were parallel before committing to drilling the holes.

I found that a drill size of 2.5mm worked well for the ABS with a drill size of 4.5mm for the railings. I then screwed the self tapping screws through the railings and into the ABS. This went smoothly.

Then the cement. I made the mistake of using quite wet sand to make the 1 cement to 4 sand dry mix. The intention was to pour this mix into the frame from all three ends and fill all internal gaps. The cement mix tended to cake when I tried to push it into the tubes. With benefit of hindsight, it would have been better to fill the various parts and then assemble them and finally compact the mix in the tubes and feed water in to activate the cement. The mix was compacted far too well! The water simply sat on top of the mix.

I now have a frame partially filled with cement mix which may or may not have cured overnight!

On the bright side, the rails are parallel with each other and the aluminium angle pieces for each end marry up perfectly with the edges of the channel!.

Next step is to drill the holes in the angle pieces to attach them to the frame.

Incidentally, if anyone in the UK needs to know where I got the appropriate materials for the majority of the McWire build, please let me know. I'll compile a list of sources at the end in case anyone will find them useful.

Maybe a sluice and premixed cement would have worked? Interesting to read your progress.

If the pre-mix was fine enough, it probably would work without a hitch. as it is, the frame is partially filled but it seems none of the mix actually set in the end. It just became tightly compressed forming a water barrier.

If I can pluck up the resolve, I might have another crack at it shortly.

I made a couple of other alterations. I'll use copper straps instead of the steel to hold the nut. If that fails, I'll have some scrap acrylic left to drill holes for the nut and fixings.

The copper straps that I bought were rather big and the mount holes were too close together. I solved both by stretching them out to around 1.3 times their original with. This reduced the height of the gap and increased the distance between mounting holes. I've marked up the first pieces of angle and will drill the holes in those tomorrow.

Thinking about it, I'll need to remove that cement mix and retry. I don't like half measures as a general rule ;D

Hi Matt,

... instead of cement you can use a mix with 6% to 10% epoxy with sand - it would better fill and grip and you can mostly adjust the settling-time by reducing the hardener-component from 30 minutes to some hours (or even days).

Look here: [forums.reprap.org]

Viktor

I would consider filling some old socks with pea gravel and just slide that into the base pipes, you could take it out when you need to, and no one would see it once the end caps are on.

Thanks for the ideas there! I'll have to take a look at the options and decide the best way to go! I'm slowly managing to extract the sand from the tubes now but it's taking a while because it's really well compacted in some areas. I'm sure it's the right choice to remove it as it wont really provide any structural stability as it's not set.

The epoxy sounds interesting to me as it would be good to be able to set it in around 60 minutes. This should give enough time to fill the frame and fix it in the correct position for setting.

As it's taken a long time to remove the sand, I've been concentrating on preparing the templates and cutting / drilling the acrylic stages. I've found that fast moving blades and drills will melt the plastic rather than cutting it (should have remembered that from Design Technology really!). I used drills in slow bursts, allowing the bit to cool for a second before drilling further and pulling it fully out to clear the waste plastic.

I used a hand saw to cut the acrylic in the end and will finish it with files, sandpaper and wet and dry paper for a nice finish.

The flange piece I ordered has different hole arrangement to the piece used in the example. I've therefore created my own version of the vertical_base template in adobe illustrator. It's attached to this post in case anyone wants to use it. It's designed for an A4 sheet of paper and DXF and PDF formats are provided for anyone who would like to use it.

I'll add versions of the other templates when I complete them. If someone needs a copy of the illustrator version of the file to adjust it for their own purposes, please send me a pm with your email address and I will forward a copy to you. I can't attach it to the post due to the file size.

That's all for now but the pieces I have assembled so far have fitted well.

Well, I've tried a couple of things today and managed (I hope) to solve the problem with the stiffness of the ABS pipe frame. I tried the resin / granules option. I bought some resin / hardener in small tubes from a discount store and squeezed it all out and mixed it, then added some budgie grit (pieces of stone / grit about 1.5mm in diameter). I measured the amount of grit required to fill the frame beforehand and emptied it into a container.

When I actually came to mix it, the glue was a lot thicker than I had anticipated. In addition, there was much too little of it! I had an idea of using a dispensing gun with the nozzle removed to deposit the mix into the frame. I carefully poured the mix into the empty cartridge and started pumping it. The mix was so stiff that it simply compressed in the tube and none exited the nozzle end. I think if I try that again I'll need to use a 50 / 50 mix by volume of resin/hardener and filler. This would require a lot of resin and would negate the price advantage from a cheaper frame.

I then returned to the cement idea. This time, I used a 1:2 cement to sand mix and added enough water to make it quite runny. I then capped the top end of the frame with one of the end caps and tilted the frame over such that the two bottom arms were almost vertical.

I then used a funnel to feed the mix in through one of the bottom arms until it was filled. I then repeated this with the other bottom arm. Following that, I used a rubber mallet to tap the frame quickly, shaking it several times to make the mix settle then refilling to the top.

Once this was done and there was little to no movement in on tapping, i sealed each end with wide packaging tape. This allows me to fit the end caps later once the mix has dried rather than trying to force them on whilst not upsetting the mix. I then removed the cap from the top (watch out with this, the mix will tend to spurt out of the top slightly!) and repeated the filling process. With a more watery mix, I naturally found excess water tended to rise to the top which made it easy to move with anything absorbent.

Once I'd topped it up, I then covered that end with tape. I then screwed the two rails back into the frame to ensure that the mix will set in the correct position. Finally, I pushed it up against a known vertical surface and fixed it in position with a few bricks. I then added a peg to prop up the vertical pipe as I'd glued it slightly off vertical when assembling. The ABS adhesive bonds very quickly so I'd recommend threaded pipes and fittings next time to avoid the hassle and save the cost of adhesive!.

I think it will work out quite nicely now so I'll be able to concentrate on assembling other parts whilst the cement dries!

If anyone's interested, I have a few sets of these plastic pieces cut to size which I could sell. (when I ordered I needed to make sure I had enough to complete if I made a mistake). If anyone's interested, let me know and I'll figure out how much they actually cost. Alternately, I'll happily give you details of the supplier so you can order yourself / search for alternatives.

That's all for now and if you've made it this far, thanks for listening!