[peteeng]

Hi Ard - I think that would be classed as a hexapod? Its like a plane simulator. But I can't see 6 arms only 3. maybe a tripod The attached doc discusses some alternative machine types vs cartesian machines. Peter

High Precision Hexapods (newport.com)

[pippin88]

Hi All - The Milli thread has been slow but I have been trying to finalise Frankie so it can leave the workshop so I can start the next machine! But another thread has pushed me down a path and Milli has woken up again. Sika have a high modulus grout which I shall assume I can get here. I shall put in an enquiry to check I don't have to buy 35T of it. Sika-3350 E-56GPa. Plus they have a self levelling grout... My rule about a part being no more than 50kg has stymed me so I think the base has to be two pieces. I have been trying to do isogrids and other grids parametrically in Fusion with no luck. So manual it is. But The base could look like the following. In T1 image the outer parts are 50% the weight of the solid base. The small holed version does better.

In T2 image the longitudinal holes do much better then the thru holes. makes sense as this is like a series of I beams... I did run a generative, but it didn't tell me much. So the long holes can be achieved by using plastic conduit and the base would be two parts held together by the "walls'. No I have to decide on the machine size and do some modelling... It became way too big last time I got into it... Peter

Peter, did you get an answer on Sika-3350 availability / minimum order?

[peteeng]

Hi Pippin - I thought I published costs here somewhere but can't find them so:
1) Bunnings sikagrout 3350 - one bag minimum order $110 aud plus, from memory was a shock
2) I was in my local hardware so asked, they called sika on the spot and it was $80aud per bag 2 weeks to get it here. So ask your local hardware that sells Sika product
3) HE80AG is about $35 per bag available per 20kg bag at Bluey warehouses E~40GPa
4) Lanko 701 class C grout Bunnings $37 per 20kg its a CSA/portland mix. Made by sika but no published modulus. So I expect around 35GPa... add 3mm blue metal and it will go up. Like HE80AG
5) sikagrout ultra E=33GPa its also self levelling CSA/portland mix

Thats about it I think... Peter

[pippin88]

Thanks Peter

3350 looks like a good choice. Only need about 4 bags, so price difference is minimal compared to overall cost of machine etc.

High modulus. Rated for thick pours up to 500mm.
Some of the others recommend max 100.

[peteeng]

Hi Pippin - The $80 local included a $20 delivery fee. I'm in a rural area and always pay some sort of cartage on special items. Even fedex charge $35usd extra because of my postcode for Chinese stuff... If your in suburbia maybe cheaper. Plus Bunnings have their price match policy... I'm sure some hunting could bring the price down... Peter

ive put the data sheet here for others. Interesting it has lots of german specs. The SDS says its "cement" with quartz (sand) I looked up its CAS and no info there either. Cement covers 100's of items. Peter

[peteeng]

Hi All - Today I infused some carbon fibre panels for a friend that makes ukuleles. The panels will be for two sound boards. Ones 0.5mm thick the other 0.8mm. He can pick the best one by sounding it. I post these here as this is the process for casting composite machine parts. Produces excellent near aerospace quality laminates. In fact this is the process of choice for new plane parts as they are out of autoclave yet they are the same quality which means they are cheaper to produce and as aircraft get bigger the autoclaves are now immense and really can't get bigger. Will strip and inspect tomorrow.. Peter

[ardenum2]

sikagrout 3350 for $100? is that 25kg per bag? That's the price of a premix EG epument from rampf. Expensive, but I guess that 500mm pour capability is the reason...

I haven't seen this classification around here. Only this one: CEM and VLH (attached)

[peteeng]

Hi Ard - I've been quoted $80aud at the local hardware for a 25kg bag. That includes a $20aud cartage charge for a special order from Sika. Seems to be good value compare to options. Or use other C class grout at $37aud for 25kg but get 35-40GPa vs 56GPa... Peter

The reason is its not a standard line for the local shops. I'm sure it's not expensive in the commercial world if I ordered a tonne. Its just concrete...

[pippin88]

Can't get epument / commercial epoxy granite in Australia.

And casting wet is easier than drying aggregate etc.

[ardenum2]

Can't get epument / commercial epoxy granite in Australia.

And casting wet is easier than drying aggregate etc.

I agree, drying 100's of kgs of sand and rocks would be a nightmare and grouts are more flowing than say uhpc, its definitely very appealing to use. You guys could order a tonne or a pallet and split it 50-50, if the price is smaller enough.

[peteeng]

Hi all- Here's the approx cost of sika vs ep granite. They are the same. If I buy the basalt at Bunnings and epoxy from my usual source. Against the sika3350 at $80 per bag. I'm surer we can get the Sika cheaper.... plus the sika is stiffer. I doubt we can make the EG past 45GPa... Peter

[peteeng]

Morning All - Released the boards this morning. Very good result. Looking forward to see what they become. Now to set up the moulds for the test coupons. Regarding water in the materials. Yesterday was warm and dry. 27degC 45% RH. Yet when the bag got down to 1000Pa the steam starts coming out of the vacuum pump outlet. This is typical. When the pressure reaches the saturation temperature point of water it turns to steam. eg at 101kPa water boils at 100C. You can look up a saturation temp/pressure chart if you like. Once it starts steaming 1 volume unit of water changes to 10,000 volume units of steam... the pressure can increase due to the volume of steam. Once the bag is dry the pressure continues down until it stabilises at 1) the vacuum pumps capability (when new it had 50Pa bottom pressure) or 2) equalisation with micro leakage... which in my case is 300Pa absolute or 300/101000=99.7% vacuum So if we started with 1 litre of air, now we have 3ml left. Thats quite a bit if it ends up in the wrong spot....Peter

I'd like to make composite gantry & other parts like this soon....

bag off - plumbing and consumables removed
peel ply off - a polyester separation ply is used so the consumables can be removed easily
mould side very nice

[pippin88]

Hi Ard - I've been quoted $80aud at the local hardware for a 25kg bag. That includes a $20aud cartage charge for a special order from Sika. Seems to be good value compare to options. Or use other C class grout at $37aud for 25kg but get 35-40GPa vs 56GPa... Peter

The reason is its not a standard line for the local shops. I'm sure it's not expensive in the commercial world if I ordered a tonne. Its just concrete...

I'm not having as much luck so far. Only local place to get back to me with a price says $151.8 per 25kg bag, 2-3 month wait as it has to come from overseas...

[ardenum2]

I'm not having as much luck so far. Only local place to get back to me with a price says $151.8 per 25kg bag, 2-3 month wait as it has to come from overseas...

what? sika3350 is supposedly only available in Australia. These guys...

[peteeng]

Hi Pippin - speak to Ewan McDougall at sika oz. [email protected] Peter

[ardenum2]

Have you seen this?

https://www.youtube.com/watch?v=6ysnAbuSwN0

[peteeng]

Hi Ard - Generative design is getting into everything. Thats where I want to go. Peter

[peteeng]

Hi Pippin - Here's his details . Peter

[pippin88]

Thanks

[ardenum2]

Pete, have you ever explored the relationship between tolerance and stiffness? Now that we have some kind of sense what the load on an endmill is, you want to make parts down to 0.05mm you got all the right motion components but how much stiff should your machine be? Am I saying this right?

Say you use an endmill with 100N acting on it during machining, so you'd need a machine that deflects 0.00x during the cut?

I might be creating a nonexisting problem...