[peteeng]

Evening all - So I think I'm at the end of my tether with the base. The only way to make it stiffer as I see it is to use an aluminium/aircrete/aluminium sandwich. Has the advantages that the top surface will be fully machined with all the registers and threads. But oil will get down into the bondline and it may unstick over time. So its 150mm thick aircrete for the moment with inserts. That weighs 102kg so OK but the inserts may unstick over time?? Better do a good job with the epoxy.... Peter

and I'm assuming I can make aircrete. I do have a colleague with a foamer so should be OK...

[ardenum]

What's more important for you, stiffness or weight? Have you hollowed out the thicker bed from the bottom like this and run a sim on it?: https://images.adsttc.com/media/imag...jpg?1450900640

[ardenum]

I have to say I wasn't too convinced by your gantry structure but I guess you were right with it. Mori also uses the design you you chose in DMF 200.

[klaas123]

It's slightly bigger though

[peteeng]

Hi All - Good configurations scale and I think the moving column is a good config. It also allows easy combination with trunnions or large rotary tables such as the Mori. This design also isolates the job mass from the motion parts so the motors can be optimised just on the machine parts weight and does not have to have reserve for the job mass.

Hi Ard - Yes I have looked at eggcrate (as the photo is called), orthogrid and diagrid earlier on. They are not as stiff as solid and require cores or countermoulds to cast (ie more complex to make). Stiffness and weight are related and they are both important in this case. With big machines like the Mori you need mass to counter inertial loads. Plus the owner does not mind using a large crane to hoist it into the shop. They don't even mind laying the correct foundation for it or the couple of Mil $$$ to buy it.

A benchtop machine ideally is lifted by two people and Milli is way too heavy for that. So its now a stand machine lifted with a car motor crane or Gantry with tackle. Or built in place. Its not about me Ard if your the customer what do you want? A light stiff machine or a heavy equally stiff machine? Peter

[klaas123]

Hi Peter, can't you make a CSA pour ready hollow base, and let the customer decide to fill it or not?

[peteeng]

Hi Klaas - Then it would not be a product with a specification. I'm thinking of cutting it way back to a benchtop machine. Maybe 200x500 which is still big for a benchtop. Peter

[mactec54]

I have to say I wasn't too convinced by your gantry structure but I guess you were right with it. Mori also uses the design you you chose in DMF 200.

peteeng design is a little different from the Mori design you are showing but close, there are many machining centers that use a similar design which has been around for 40 years there is not much that is new in machine designs that have not been tried in many different configurations for machines of all kinds the latest in Mori is there gantry machines DMU 200 Gantry and the DMU 340 Gantry come in many different configurations both are superior to this old design

[peteeng]

Hi Mactec - Nice vids. I think I'll order the Mori now, will be perfect for making Milli parts... I've been wondering about the stacking efficiency of my steel fibres. I have done some process tests that are good but the density is not there yet. So this morning I did some dry filling tests in known volumes and its tough to get it past 15% volume ratio. They must be furry and interlocked... This means its estimated stiffness is 200x0.15*0.5=15Gpa which is no better then the raw CSA at 26GPa.So CSA and granite is the go so far at 40GPa... Peter

[ardenum]

Its not about me Ard if your the customer what do you want? A light stiff machine or a heavy equally stiff machine? Peter

Ah, my bad, I must have missed that your building this for someone, gotcha. Since it's the customers wish, I guess your only option is 'as stiff as it gets' with the weight limit. As I understand the customer also wants a bt30 cartridge? You could shave off a lot of weigh from cartridge+motor if you went with a motorized spindle, of course I mean something rectangular from e.g. Teknomotor or Hiteco, and not something that goes for 5k+.

You can 3d print cores or countermoulds, if you print in something strong like nylon or CF nylon, you could print them hollow, I'd think a 5mm shell would be strong enough to not bent under the concrete.

peteeng design is a little different from the Mori design you are showing but close, there are many machining centers that use a similar design which has been around for 40 years there is not much that is new in machine designs that have not been tried in many different configurations for machines of all kinds the latest in Mori is there gantry machines DMU 200 Gantry and the DMU 340 Gantry come in many different configurations both are superior to this old design

There's a lot of things you can't diy manufacture with DMU 200 and DMU 340, I looked extensively into Gantry designs and I have to say if one wants to use EG or CSA, the design choices are very limited. If someone wants a benchtop machine then a Datron style gantry is the best space saver. I'm not sure if peteeng would be interested in welding the gantry himself.

I was supposed to go with a datron-esque gantry myself, but then decided I want the versality of cartridge+motor and switched (after a a wise suggestion) to a double column lifting gantry. Both are great space savers, but datron style machine is probably lighter.

Hi Klaas - Then it would not be a product with a specification. I'm thinking of cutting it way back to a benchtop machine. Maybe 200x500 which is still big for a benchtop. Peter

Here's something that melts aluminum and is benchtop, Not sure about the weight though.

[peteeng]

Hi Ard - Its a production machine so making fibreglass moulds is no big deal if that's what it takes. 3D printing shells would take forever in production at the moment, even on fast printers. Thanks for the ideas, I think I'll scale back a bit...Peter

[ihavenofish]

I have to say I wasn't too convinced by your gantry structure but I guess you were right with it. Mori also uses the design you you chose in DMF 200.

mazak and brother use it too.

its a very good layout, but more difficult and expensive to implement than the basic C machines.

you can buy used brother TC321/323/324 machine for like $1500 if you want a small but high performance frame like this. they have a rotating pallet table and a crazy fast 10/14 tool atc with a bt30 spindle. even if you treat the machine as "castings" and throw away every other part, you're going to be better off by far than trying to duplicate this on your own at a hobby level, unless you make it very small and weak.

of course thats no fun is it? :P

[ardenum]

mazak and brother use it too.

its a very good layout, but more difficult and expensive to implement than the basic C machines.

you can buy used brother TC321/323/324 machine for like $1500 if you want a small but high performance frame like this. they have a rotating pallet table and a crazy fast 10/14 tool atc with a bt30 spindle. even if you treat the machine as "castings" and throw away every other part, you're going to be better off by far than trying to duplicate this on your own at a hobby level, unless you make it very small and weak.

of course thats no fun is it? :P

You deal with used machines?

also when it comes to benchtop kings, how cool is that.

[ihavenofish]

i had 2 brother tc's, but the c frame style. i just sold them cause i moved

[peteeng]

Hi Ifish - Maybe used machines are around in Canada but in Oz none. That mini Heller HMC with rotary is very cool. Perhaps Milli should be a HMC? We are having fun aren't we? Peter

Hi Ard - Abel machines very nice. A little above hobby/maker grade machines. Wouldn't call them benchtop but lovely to look at. UHPC is good. Peter

[ihavenofish]

Ah, yeah. my friend is in NZ, and if i wanted to GIVE him one of my brother machine it would cost him $10000.

Anyhow, didnt mean to sidetrack to buying other machines. just was pointing out that format was great and if you wanted a bigger beastie one, youd do well to start with that.

For you, id say look at their frames. I think you could learn a lot of the way they do things, because they take a "light" bt30 with small linear rails and ball screws machine and make it outperform almost eveything else.

A substantial base is one of the key design points. they aren't thin plates on a table like a tormach, its 2 feet deep. Likewise the column. the column on my TC 229 is 16" wide, not 7". Rail spacing is big. they use small 25mm rails - same as my xzero router - but they space them, and the blocks to create stability. the Y rails are 17" apart, blocks 13-14" apart (outside measurement of blocks) - Y travel is only 12".

You get the point here. they are very clever where they put the minimal material in that machine.

[ihavenofish]

horizontal has some benifits, but you leave the user basically with no table. they have to build or buy a work holding system and those tend to cost a fortune as they are geared to high volume production.

[peteeng]

Hi - Looked up the specs for UHPC and its a Portland blend E=40-50GPa depends on what you add to it. So much the same as CSA. CSA is more stable because there's no Portland in it. I also will post cure the CSA so its very stable. I did start this with a gantry or bridge machine in mind but you can go back and see how this thing developed. Every configuration has pros and cons. You pick your envelope and config and keep chewing it until you get an answer. I do like the idea of a fixed job ie fixed table vs moving the job that's one driver in this project... Peter

Hi IFish - yes a substantial base is a common theme here. The foundation has to be good or the rest suffers.. Peter

Hi Ard - I'm fully capable of welding machines in Al, steel or titanium and I have heat treatment and other facilities close by so can process these as needed for machine parts...But I do not think this is the way to go for many reasons. Thanks for watching. Peter

[peteeng]

Hi All - Its much much easier to build a stiff big machine then a small machine. A big machine already has geometry. For every 1.2x you make something bigger you double its stiffness/rigidity. So something 200mm deep make it 240mm and its twice as stiff. Make it 288mm deep and its 4x stiffer. But these all have knock on effects with bearings, bolting flanges, access holes etc etc. Its easy when you have a set envelope and target stiffness and the footprint does not matter. You just make everything big and wide and it looks after itself. So small machines are tougher, as I'm finding.... but I'm still smiling... Peter

and Ard - they all show machines ploughing through aluminium, I want to see what they do with steel. Especially Datron...

[ihavenofish]

there are datron videos in steel, by they are micro tooling moulds. datron's limitation in steel is the spindle. just too fast.

ive seen comparatively flimsy hobby routers do well with adaptive clearing in steel, when they have the right spindle speed and torque range.