[peteeng]

Muffs - All done ready to work again. Peter

[peteeng]

Back to Mili-Pede - Morning All - I want the column to be very aerospace with isogrids and curves. It will be asymmetric to lift the vibration modes. The front rails maybe symmetric but the back has to be asymmetric. Problem is modelling it in the best way. The first time rarely works.... Gets the creative side going. This one: Round 4 is a loft from the bottom to the top then pocketing for the ribs. Need a way to automate the patterning so many glitches to fix and so many fillets to put in... Next one will be better... Peter

I have not been able to find out why they put the small circle at the cell ends. I understand if its a casting so as to provide some give in the webs so it does not crack on solidification but these things are milled....any clues out there?

https://forum.nasaspaceflight.com/in...opic=41016.380

[peteeng]

Isogrid Nodes - Found out that the hole is used for attaching things to the grid. They are redundant features so if something needs to be attached it can be without modifying the structure or if you remove something it does not change the structure.

too big to upload see:

https://femci.gsfc.nasa.gov/isogrid/...rid_Design.pdf

[peteeng]

Afternoon all & Sundry - So I thought I may be able to use an isogrid structure if the column was shear dominant. Being short it maybe a shear beam vs a long beam. So I modelled a solid column of same dims as Mili, a hollow one half the weight and a holy isogrid half weight of solid. (Solid 175kg, others 86kg) Applied bending and torsion loads to see what happens. The solid bent 0.42mm the hollow 0.60mm and the iso 0.54mm very encouraging. But in torsion the solid moved 0.08mm the hollow 0.11mm and the iso a disappointing 0.30mm. So Hollow it is and I'll have to figure out how to do that best.... Peter

[Zorbit]

Isogrid with skins ?

[peteeng]

Morning Zorbit - Yes its a solution but harder to cast> I loaded the last good column model into the block comparison to see where it fell. I also reviewed current costs. The current design sits well with the others and is better then the block. Torsion has always been the bugbear> Costs? The kg cost of dry carbon was a good surprise, but have to buy in rolls to get a good price. A roll weighs 50-60kg so at $57AUD/kg its a big layout and twice as expensive as aluminium (by volume)... I'm waiting on the short fibre CF supplier to get back to me.. I'm back to thinking about an Al plate machine.... circular thoughts. Best to get PlankNo2 done to settle the alox future... Peter

[peteeng]

Morning All - The column topography has been leaning towards plate aluminium construction so here it is. The column weighs 100kg which is good and its stiffness is X 45 Y 36 and Z 94. I can improve Y I think. I could make the plates out of FG or CF but the FG ones would not be as stiff as the AL and the machinists would not like it. Better get PlankNo2 on the way... Peter

[peteeng]

Hi All & Sundry - Dropped into the local stonemason today to discuss granite chunks for the base. To get a 750x750x100mm thick piece he'd have to order from China and he wasn't keen on this sort of work. Couldn't get him to talk $$$ or much at all. So onward to casting and lapping my own.... Peter

[peteeng]

Re: Update in granite- The stonemason did give me the national contact for the granite so I gave him a call and he's an ex machinist so knew what I was about. Turns out granite is cheap. Its $4500AUD per m3 which is the cheapest material out there. China will cut to size and make one surface flat and level... 8 weeks lead time. May rethink a couple of things. So I called about steel and checked the other costs. So cheapest to dearest - granite, UHPC, steel - alox, eglass, Al, CF Peter

[peteeng]

Hi All - I was really surprised by the low cost of the granite so I called him back and asked him to check his figures which he did and he confirmed the quote was correct. We then talked about holes and cutting to various shapes. He said happy to quote just send in the drawings. Maybe a viable production route.. sad if this goes to China but then that's where I get my bearings and motors.... Then its back to what the modulus of the material is.... have to get some and test hurdy gurdy....Peter

[peteeng]

Interesting thesis on machine stiffness - Peter

[peteeng]

Evening All - Been out today to see some clients and attend a company show. One of the local laser companies has moved to new premises and had a trade day today. Haven't been to them in a long time so I headed off to see the new place. Surprise, surprise they are also the national distributors of HAAS and have combined their lasers and HAAS in one showroom. Even on the laser newsletters they have never mentioned they distribute HAAS. So was a double happy day!! Their two top lasers had super speed and 5g accel. Watching it rush across 4ft and back in a blur was quite fun. Then took the tour of the mills and the 5 axis was running sample pistons of which the operator gave me one. Cycle time 12mins!! A fun day. Peter

[peteeng]

Afternoon all yuz out there - A friend of mine that I have been building extreme bikes and parts for, for over 30 years dropped in today with his latest project. Its a 3D printed Ti bike frame with specialty tubing. The tubing is CF with nano fibre reinforcement, max thickness 0.6mm. The Ti printed stuff is a bit heavy but very nice. The frame will be a mid size frame about 600g light. The 3d printed parts cost over $7000AUD and half the tubes came from Switzerland and half from New Zealand. I designed the layups and will do some FEA on the next frame. His heading home to set up his jig and epoxy it all together. But his keen to get the Ti polished or anodised. It will be up to his usual amazing quality... Peter

Ti printed router Hmmmmmm

[peteeng]

Hi All - Been busy finalising the parts for the new router. Have received all the quotes and will place orders tomorrow. Then I wait 7 weeks for the bits. So some time shall open up to get back to casting Plank2... I'm thinking of talking to the granite people and trying to get a very thin long piece to do a flex test with. Onward and upward as they say. Peter

[ardenum]

Hey peter

What do you think about modularizing the side rails and table to cut on shipping and handling weight like this, and have the customer cast a simple UHPC/CSA block with anchors...?

[peteeng]

Hi Ard - Good thought. The more work that can be moved to the Maker the better is one philosophy. But then you run the risk of diluting your product. Once the machine design is nailed down better, breaking it down is easier. Still not at a happy place yet! Plus have not solved the problem of economy alignment. Those big mill parts will need laser aligning. Been looking at scanners... Peter

[CCM506]

belt-driven linear module easy setup for CNC, www.ccmrails.com

[peteeng]

Evening All & Sundry - Not sure if I've put this up before. Its a study done on many types of rocks and uses tensile testing to establish modulus. Granite has a big variation but the right stuff is very stiff, much stiffer then aluminium (>100GPa) and similar density (~2900kg/m3). Question is how to get the right stuff? Peter

[peteeng]

Hey All - Here's a piece of the steel fibre reinforced CSA that I cast a while ago. Its been outside in the weather but it would still have rusted inside I think. Steel hasn't worked out in several ways.... Peter

[peteeng]

Evening all you motley lot - Well we have been discussing casting machine parts and Elon has been very busy building the biggest pressure casting machine in the world. Tesla cast the entire rear and front of a car in one go.... a great muse.



Time for some ZZZZ's Peter