John's Alu Profile build

[Evengravy]

Okay,

So a bit of progress. I slowly managed to get the walls built for this machine base. I ended up mixing small batches of my previous glass reinforced mortar mix, essentially just scaled up to larger batches and continued building one layer at a time, leaving a couple of hours between layers to allow mortar to go off slightly.

I ended up with 3.5 blocks long per layer and five layers high in total, to bring it roughly to waist level. I began by pre-cutting the granite/concrete blocks with a diamond disk on the 4" grinder and cut around the circumference in the centre, blocks were then easily separated into pretty clean halves through some brute force with a bolster and club hammer. It doesn't take a huge amount of effort in reality. I certainly won't win any awards for my block laying skills, but this mortar is more difficult to work with tidily than regular mortar due to the glass fibre input. It should be worth the effort I feel as it is tough stuff, so I don't see any issues with it. It should mostly be under compression here so hopefully shrinkage will be a non issue later. We'll see I suppose.

I tended to try and keep the mixture on the drier side. It is more difficult to manage that way but I feel this will be a good approach in terms of the overall strength. The water volumes are only a guideline really, in practice each batch will differ slightly so half is added, and gradually added there after to avoid making it too wet. With the super-plasticiser it's easy to overshoot the water addition and end up with a mix which has too much flowability.



I ended up leaving some space around the perimeter in order to facilitate access and to allow sufficient room for any future enclosure.



Thanks Clive for the heads up on SBR, I've purchased a gallon of that to treat the floor and paint it later. I'll likely get the messy 'table-top' casting out of the way before I do that though. That's the next job on the list.

[Mister Mills]

Not long now John........... Looking pretty sturdy! I have been goosed for time myself but have started do do a few bits as stuff arrives. Delivery times are dreadful :(

[Evengravy]

Ah, it's slowly taking shape. Thanks Liam. Can't imagine it's going to fall over any time soon so I'm pretty happy it worked out. Next job is sourcing some plywood and steel rebar so I can prep a mould to cast the top. All being well I hope to get started on that this weekend if I can get everything I need. I'll need to buy some more cement and check on the status of my plasticiser order, it should be here soon.

I ended up ordering some more motor couplers from a European source this time, third time I've ordered these similar parts now which has been both annoying and unnecessarily costly but I don't hold much hope of anything I've ordered from China ever arriving to my door. I'm a cynic in general but part of my thinks this whole thing is really about putting a pin in Chinese manufacturing dominance. Maybe that's a good thing for us and this particular interest but anyway, maybe I'm just getting too cynical as I get older.

Anyway, if this order doesn't come through I'll definitely hit you up about those couplers again if they come through to you. I'm hoping mine will be here in the next few days so I can finally test the ballscrew install.

[Mister Mills]

Hi John, My order arrived last week. A month late!!!!!!!!!!!! I have 3 pcs of spare 8 to 12 mm couplers. PM me your details and I will pop them in the post if you still need them.

My motors and atc wont be here for another 3 weeks at least :( so I well know how much of a pain it is to be waiting for stuff to arrive.

I agree with the whole cynical outlook. It's true haha. Same myself.

[Evengravy]

Thanks, I'll give these ones a few days and if nothing by the end of the week I'll give you a shout. The first order I placed was at the start of April so I doubt they're disappeared somewhere at this stage. Thanks a lot though!

[Evengravy]

More progress made over the weekend. I didn't quite get to the table top pouring but have the majority of the prep done. I also received the ballscrew to motor mounts (finally) so was able to install and test those. No issues so far, noise is greatly reduced and I have it running up to 6 meters/min currently. Beyond that I get stalling but may be able to tweak it a little more later.

Next step in the table build was to build a mould for the concrete top which will be cast soon. I'm awaiting some more super plasticiser but that should be here soon. Calculating the approx weight it will be in the order of 400KG when cast, so my first concern was bracing the open section well.



I chose to use studding which was left over from the building of the workshop in which this machine resides. I made up three sets of braces one for each side and a beefier version for the middle section. I chose to do this with the consideration that it needs to be knocked out from underneath later: I want it to be solid but also removable after the fact. There were some additional braces between these sections that isn't shown here.

On top of this some 11mm ply was set and sealed with silicone between joints. I chose to have the ply a little lower than flush with the walls, this might be difficult to see in the photographs but the idea is that the concrete pour will step down 10mm (vertical) over the end of the block walls before meeting the ply on the inner side of the blocks, creating a key of sorts. I thought this would add some additional strength.



Toward the front I added some 34mm (I think) plastic conduit so I can cleanly route a few wires from left to right (front left Y motor and home/limit switch). This is cut to be a tight push fit against the ply walls, which are fixed to the walls with masonry nails and a 600Kg ratchet strap is added for additional support from bowing. I also ran some lengths of string through the conduit/pipe and fed these through the ply walls at each end such that I can easily pull my wiring through post casting later.



All the wooden surfaces that will be removed were given a couple of coats of beeswax to function as a release agent to aid removal post concrete pour.



Lastly, high tensile steel rebar was added in an overlapping cross pattern. I chose to tack weld these together with the ARC welder and prop them up towards centre (ish) with some rock that can stay in situ as I cast.



I've got a few little gaps here and there to fill with silicone but as soon as the plasticiser arrives I should be good to go on the casting of the top section. I roped my brother in law to help out, likely it will be Saturday next when I get started on that bit.

[Evengravy]

Not sure if anyone's still following along, but I'll pop stuff in here regardless for sake of completion.

Concrete top has been poured. All in all it wasn't very difficult with the help of my brother in law and a cement mixer. I ended up pouring just over 500KG of my initial glass fibre mix scaled up. I was a bit nervous that the mould wouldn't hold up to the pressure/weight, but it seems to be okay (touch wood).

Just for reference, the mixer held:

50KG of sand
50KG cement
to this I added:
150g of super plasticiser
1.5KG of glass fibre
circa 8L of water, added gradually to play the mix by ear a little.

I ended up with five of these mixes in total in this top section. I don't envy the person that has to remove this, and hope that it isn't me....



I've covered this in plastic sheet (not shown) to prevent it from drying out too quickly so that it can cure properly and I'm going to have to give this a mould at least a week before touching it. What I'll likely do is leave the mould sides in place and cast the epoxy top before removing the sides. I do need to do some careful figuring out to maximise the use of my z travel though. There may be a case where I'll have to increase the height of the Y rails to this top to give me sufficient clearance to fit my vice etc. but that is to be determined and most likely unnecessary.

[Kitwn]

I don't envy the person that has to remove this, and hope that it isn't me....

Don't worry. The next owners of the house can turn it into a poole table

Looking forward to seeing the final machine and how you make the gantry to match the base.

[Evengravy]

Don't worry. The next owners of the house can turn it into a poole table

Looking forward to seeing the final machine and how you make the gantry to match the base.

That's a good point! Next up epoxy layer, I'm still looking around for materials atm. If anyone has any heads up on a low viscosity resin I'd appreciate it. I used one years ago on the Momus CNC base but completely forget the manufacturers name. I'm sure I'll find something though.

[Clive S]

That's a good point! Next up epoxy layer, I'm still looking around for materials atm. If anyone has any heads up on a low viscosity resin I'd appreciate it. I used one years ago on the Momus CNC base but completely forget the manufacturers name. I'm sure I'll find something though.

Wests system https://www.westsystem.com/the-105-s...ins-hardeners/