Yet another epoxy granite mill

[badhabit]

I had planned the injection of epoxy into the design via the two tubes in each side of the column-feet. I also planned to use a special epoxy design for this task, it contains a large amount of very small steel particles. [...] https://www.diamant-polymer.de/en/products/dwh/

I talked to the local distributor of this DWH 310 FL epoxy today and they told me that there currently was a deliverytime of up to 6 weeks, so i placed an order for 2x 500g now, so hopefully it will arrive just before i'll need it :-)

[stef110]

Im jealous on your mold build.
I also used the dwh310fl to settle down the column. I hope its not to late but its a pain in the ass, to get the epoxy between the plates. if you still have the possibility you should add some tubes that run to the middle of the plate/feet so you can insert the epoxy from the middle out.
At least that's what i should change next time i build a machine this scale. I belief your mounting plates are even bigger.

Stef

[badhabit]

Im jealous on your mold build.
I also used the dwh310fl to settle down the column. I hope its not to late but its a pain in the ass, to get the epoxy between the plates. if you still have the possibility you should add some tubes that run to the middle of the plate/feet so you can insert the epoxy from the middle out.
At least that's what i should change next time i build a machine this scale. I belief your mounting plates are even bigger.

You are jealous of my molds?! haha, oh the irony, you are the one to "blame" for me building a machine in the first place! ;-) I saw your buildlog and the "machine envy" hit me hard!

But cool you also used the same epoxy! That gives confidence... I saw pictures of you strugling with getting the epoxy in, so i've already added two holes in the middle of each plate for some small soft pvc tube that i'm going to embed in the casting. When it's time to lock-in the column, hopefully i can inject the epoxy from the middle-and-out with a syringe(or something) via these tubes...

My plates are 400x300x40, so i think they are a bit bigger...but the problem is the same :-)

Thanks for the heads up anyways!

/Thomas

[stef110]

oh well maybe is should beter read your posts you already talked about it
Sorry that i made you need to build this beast XD you wont regret it.

Stef

[ardenum]

Did you get your air tank already? In case you didn't I found these really cheap ones at https://www.linnemannschnetzer.de/ai...re-vessel.html

thinking between 40l and 60l.

They have steel ones too but I don't see a point in adding weight where its not needed.

[badhabit]

Did you get your air tank already? In case you didn't I found these really cheap ones at https://www.linnemannschnetzer.de/ai...re-vessel.html

thinking between 40l and 60l.

They have steel ones too but I don't see a point in adding weight where its not needed.

Ah, very nice! I've actually looked quite a lot, but couldn't find any that made sense... but these look awesome! Thanks for the tip!

[ardenum]

Ah, very nice! I've actually looked quite a lot, but couldn't find any that made sense... but these look awesome! Thanks for the tip!

Now that saves quite a bit of $ that can go towards a compressor, still looking for that though...it's gotta run both the braking system and the tool changer plus the losses.

[ardenum]

Now that saves quite a bit of $ that can go towards a compressor, still looking for that though...it's gotta run both the braking system and the tool changer plus the losses.

I'd love something like this but without the motor, so we could run it with a regular axis servomotor but I don't really know what the front part is called, any ideas? :

Otherwise I can see a lot of commercial compressors use this type of pump:
https://www.alibaba.com/product-deta...1f57RjJbro&s=p

[badhabit]

I'd love something like this but without the motor, so we could run it with a regular axis servomotor but I don't really know what the front part is called, any ideas?

Don't you want to run compressed air to your entire shop? And not only for your mill? Unsure if i misunderstood your intentions here :-) I've been wanting to upgrade my shop airsystem for years... this new mill-project will finally....FINALLY...make me do something about it, since it won't work at all without compressed air...

My plan is to buy a small screwcompressor since it needs to run in a residencial area(my back shed ;-) ), so it needs to be very silent. I've been looking at these for quite a while: https://www.cp.com/content/dam/brand...6999610420.pdf since i have a local dealer of those... i've been looking at the "CPM 5,5" with compressor, tank and dryer...

[ardenum]

Don't you want to run compressed air to your entire shop? And not only for your mill? Unsure if i misunderstood your intentions here :-) I've been wanting to upgrade my shop airsystem for years... this new mill-project will finally....FINALLY...make me do something about it, since it won't work at all without compressed air...

My plan is to buy a small screwcompressor since it needs to run in a residencial area(my back shed ;-) ), so it needs to be very silent. I've been looking at these for quite a while: https://www.cp.com/content/dam/brand...6999610420.pdf since i have a local dealer of those... i've been looking at the "CPM 5,5" with compressor, tank and dryer...

Shop? what shop? right now I have no place to put any machine in. I'm looking to buy a cheap concrete garage 3x5m and only put a milling machine inside. With shop machines its like with screwdrivers, they pile up fast, you don't know when you got so many over the years. I don't like clutter at all.

Another thing is I want to fully sound proof my machine. I mean really put soundproofing foam tiles all around it. That's how much I like noise. Having said that thanks for that info on screw compressors didn't know that was a thing, and its pretty quiet so now I know what to look for.

Originally I wanted to put a small compressor on the machine itself but maybe I could put one of these on the wall and soundproof it, that's an option.

By the way, I see in these listings "+dryer" what's the deal with this?

[badhabit]

... That's how much I like noise. Having said that thanks for that info on screw compressors didn't know that was a thing, and its pretty quiet so now I know what to look for.

Originally I wanted to put a small compressor on the machine itself but maybe I could put one of these on the wall and soundproof it, that's an option.

By the way, I see in these listings "+dryer" what's the deal with this?

The noise from screw compressors are very different from the one pistoncompressors make. So besides making less noise, it is also a "better" noise. However, expect them to be $$$ :-( The 5,5kW model i posted a link to is somewhere around 4000EUR("everything included") for reference... There is a lot more to compressor-selection than just noise, e.g. cycletime, but that is a whole other rabbithole :-)

It's an advantage to dry the compressed air to avoid moisture to build up in tanks, pumping etc. This water will need to be drained and can find it's way into equipment which can be (very) bad. Depending on the amount of air used and the weather, this can be quite a lot of water! (For more: https://en.wikipedia.org/wiki/Compressed_air_dryer )

[badhabit]

Did you get your air tank already? In case you didn't I found these really cheap ones at https://www.linnemannschnetzer.de/ai...re-vessel.html

thinking between 40l and 60l.

They have steel ones too but I don't see a point in adding weight where its not needed.

I just want to let you know that i just ordered a tank from them :-)

I went for a 40L steel-tank with welded brackets. A buffer of 40L will give me <10% fluctuation in pressure when the z-axis goes from top to bottom, i think that is low enough variation in my case. The steel-series also had ports in all the right places: Two at the top for the connection to the cylinder(i'm using two pipes for lower resistance), one at the bottom for draining, one on the side for input from the pressure regulator and finally another on the front for a pressure sensor for the control-system. I also like the way the brackets are on the steel series, makes mounting on my column easy...

Again, thanks for tip! :-)

[ardenum]

The 5,5kW model I posted a link to is somewhere around 4000EUR

Whoa that is a hefty price, I took a brief look at screw compressors and found out they have a tendency to put out oil with the air since the screws are covered with oil. On the other hand I found a compact compressor for 900EUR from Junair (https://www.esska.de/shop/JUN-AIR-Le...992920000-9810). A little over what I was hoping to pay but it works at 35 dB. The search continues.

[badhabit]

Whoa that is a hefty price, I took a brief look at screw compressors and found out they have a tendency to put out oil with the air since the screws are covered with oil. On the other hand I found a compact compressor for 900EUR from Junair (https://www.esska.de/shop/JUN-AIR-Le...992920000-9810). A little over what I was hoping to pay but it works at 35 dB. The search continues.

yeah, well, those types of compressors you are suggesting are not usefull for this, not for me at least.....11L/min@8bar for the one you linked...that is waaaaaay to small to drive anything i have. Lets say the 40L tank i ordered should sit at 8bar, then it would take 40L * 8bar / 11[L/min] = 29minutes just to fill the tank...and on top of that it only allows for a 50% duty cycle(15min on/15min off), so it'll take an hour to fill it ;-) Maybe i could live with that since it won't need any air after pressurization, but i also have pistons inside the toolchanger and the toolclamping in the spindle is also pneumatic...and there is a airseal in the spindle that requires constant airflow...and i was also planning on using aircooling for some cuttingtools which requires a huge amount of air...and a airblast-gun is also handy for clearing chips... it requires a LOT of air when everything is added up...

I think anything below 100-150L/min@6bar will be annoying to use for any sizeable machine. I'm planning on using hand airtools in my shop/garage aswell, so i'm looking at 400-500Lmin@8bar...and if i have to consider my next door neighboor then a screwcompressor is kinda my only real option because of the relative low noise level...

The oilmist is not an issue unless you need the air for painting, airbrushing or similar, but that can be easy fixed with a inline filter...

/Thomas

[ardenum]

yeah, well, those types of compressors you are suggesting are not usefull for this, not for me at least.....11L/min@8bar for the one you linked...that is waaaaaay to small to drive anything i have. Lets say the 40L tank i ordered should sit at 8bar, then it would take 40L * 8bar / 11[L/min] = 29minutes just to fill the tank...and on top of that it only allows for a 50% duty cycle(15min on/15min off), so it'll take an hour to fill it ;-) Maybe i could live with that since it won't need any air after pressurization, but i also have pistons inside the toolchanger and the toolclamping in the spindle is also pneumatic...and there is a airseal in the spindle that requires constant airflow...and i was also planning on using aircooling for some cuttingtools which requires a huge amount of air...and a airblast-gun is also handy for clearing chips... it requires a LOT of air when everything is added up...

I think anything below 100-150L/min@6bar will be annoying to use for any sizeable machine. I'm planning on using hand airtools in my shop/garage aswell, so i'm looking at 400-500Lmin@8bar...and if i have to consider my next door neighboor then a screwcompressor is kinda my only real option because of the relative low noise level...

The oilmist is not an issue unless you need the air for painting, airbrushing or similar, but that can be easy fixed with a inline filter...

/Thomas

You seem to know your stuff, I've been trying to find resources about the whole pneumatic/hydraulic counterbalance and how it works but only finding bits and pieces of information here and there doesn't really help. Any guides or videos you went over to understand how exactly it works and exactly what parts are needed in the system?

[badhabit]

I've been trying to find resources about the whole pneumatic/hydraulic counterbalance and how it works but only finding bits and pieces of information here and there doesn't really help. Any guides or videos you went over to understand how exactly it works and exactly what parts are needed in the system?

Well, i'm an engineer by heart and education, so i kinda "just wing it" :-) Common sense and math takes you a long way :-)

There isn't much to it actually. Estimate the weight of the z-axis and then find an aircylinder that can deliver the force required to hold that weight. Make sure you do the calculations for a lower pressure than what you have, so i'm going to run 8 or 10 bar in my shop, so i designed the counterweightsystem to run at 5-6 bar, this gives me the option to increase the pressure if the z-axis is heaver than estimated...

[badhabit]

I made a little progress the last couple of days. I found that the floor where i'm to do the casting process is rather uneven which had me worried that it would "twist" the mould during casting, so i decided to make a steel platform to put the forms on. Besides leveling the form, it also makes it easier to move the casting afterwards with a palletjack and it allows for good aircirculation later on in the postcuring process...So i made a steel frame and welded feet to match the floor at each point:


The steel frame was designed so it aligns with the wood grid support:


This is likely way overkill, but this is where the journey of building the forms and setup led me :-)

Then the forms are then put on top:


I stole a bakingform from the wife(shhh!) and started cleaning a gazillion M6 and M12 anchors in acetone:


In went the big steel inserts and i've started to mount the ancors. All the steel inserts fit perfectly! Kinda surprising ;-)


This is all coming together now, i've arranged with a couple of buddies to help with the casting on sunday....so i'd better finish up those anchors!

/Thomas

[ardenum]

Well, i'm an engineer by heart and education, so i kinda "just wing it" :-) Common sense and math takes you a long way :-)

There isn't much to it actually. Estimate the weight of the z-axis and then find an aircylinder that can deliver the force required to hold that weight. Make sure you do the calculations for a lower pressure than what you have, so i'm going to run 8 or 10 bar in my shop, so i designed the counterweightsystem to run at 5-6 bar, this gives me the option to increase the pressure if the z-axis is heaver than estimated...

What about other system components like valves, regulators etc.?

[badhabit]

What about other system components like valves, regulators etc.?

Well, a pressure regulator can be bought in almost all major "home depot"-like stores. So my plan was just to get one of those...didn't do much thinking on those parts....fittings etc will also be needed...but i'll cross that bridge when i get there :-)

[StrawberryBoi]

I assume he's running a manual regulator, but you could also use a controlled valve. Since he has an accumulator he's made a 'constant force' gas spring system. The accumulator will add enough capacity that he could use even slow-ish binary control on a valve and not need a proportional valve at all, as long as the valves have enough restriction (ie, small!).