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6 Attachment(s)
Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
My last project was converting a PM45m (RF45 clone). Exceeding the performance envelope in every way of my Rf45 clone is the base line goal while being on a budget.
Old mill I am going to replace with this build:
Attachment 269762[
I have been accumulating components over the past year. I have come to hate dovetails and am going with linear guides:
THK SHS30 for X axis 18”/700mm travel
THK SHS 20 for Y&Z axis 20”/780mm travel
I am going to be using either THK or NSK -32mm ground ballscrews
Epoxy granite for all major components and use of precision ground steel plates cast in place for the linear rails, servos, ballscrews etc.
Here is the basic design. I am using simple straight forward forms for the molds and incorporating plumbing in the casting to provide for lubrication and cabling:
Attachment 269742
Attachment 269744
THK Linear Guides- I have a longer section of rail coming Monday for the short one:
Attachment 269752
Here is a pic of the mold for the base with the 1/2" thick precision machined steel pads that are being cast in place for the linear guides:
Attachment 269754
The steel is ground to .001" on all sides and 1/2"x3"x36". Each bar weighs a lot. I am aligning the bars and bolting them to each other with the cross members embedded in the epoxy for strength. That way I can pre drill the holes and fix them precisely by bolting them through the mold using coupling nuts which will serve as anchors for them.
Attachment 269756
I have 5 gallons of US Composite 635 and slow hardener coming- I will try to finish the mold for the base this weekend and drill and align the steel pads for the linear guides.
More to follow but I will probably try to go with a 10hp spindle and 10k minimum rpm.
I am still finalizing the epoxy granite mix but have built molds with melanine coated board with composites previously.
This is going to be a heavy machine...
Thanks for looking- suggestions are very much appreciated.
Mark
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
that going to be heavy machine good size too look forward to seeing more
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Quote:
Originally Posted by
daniellyall
that going to be heavy machine good size too look forward to seeing more
Thanks for your interest. The base alone is 19"x37"x8" (482mm x 940mm x 203mm) deep epoxy granite with re-enforced steel and the ground plates embedded.
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Looks interesting. How will you align the two segments perpendicular?
Are the linear guides purposely ordered do did you happen to pick them up for a good price?
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
I'm finding these epoxy builds fascinating, I'll also be following your progress with this, it sounds like a great project.
cheers, Ian
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2 Attachment(s)
Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Quote:
Originally Posted by
Voyager77
Looks interesting. How will you align the two segments perpendicular?
Are the linear guides purposely ordered do did you happen to pick them up for a good price?
The point of using the 2 big ground steel bars in the design is to provide a way to line everything up- the y axis rails, and the the column for the z axis both sit on the same precision ground bars to .001".
First I am aligning the two 3x36x1/2 precision ground bars parallel using a 12" granite surface plate. Then I will align them on the same plane by cross bolting 1 x 1 precision ground bars to fix them in place aligned.. Once cast into the epoxy base this assembly forms the basis for both the y axis and the vertical column for the z axis which will also use 2 ground steel bars aligned the same manner as the base.
Finally, I am going to cast in place a 15x15 ground plate on the bottom of the z axis. After reading about using grouting for alignment, I will use this method and have jack screws to do the final adjustments and then grout.
All the ground bars are being drilled and will be through bolted in the mold using coupling nuts to hold them in place.when I cast the epoxy granite. This should provide a precision ground and aligned surface to do final indicating of the rails.
Today I managed to drill the steel bars for the 30mm linear rails. I was worried about the prospect of drilling 18 holes through tool steel all aligned but it worked. I had to do 3 different setups on my rf45 clone for each rod. I bolted one of the linear rails direct to the table and indicated it straight and then used that as a straight edge for steel bars. Really made me wish I had a bigger mill! At the end, every single hole witnesses the linear rail holes.
Attachment 269906
After all of this is done, the column will mount on the bars cast into the design. The base of the column will be a precision ground 18x18x1 plate cast into the that will also sit on the rails - I have to drill those in a different pattern.
As far as the size of the linear rails, they were selected on the basis of the largest I could afford and fit in the design. I got all of them on Ebay and they were new stock. I averaged 200 per axis for rails and guide blocks.
The Y axis has the most forces on it because it has the x on top so I went with the extended version THK SHS30. They are going to be 15" for maximum rigidity. I can get a decent amount of deflection cutting steel on the RF45 and this is one area I wanted to really improve.
The X and Z have less force and going with the 20mm THK SHS to provide more range of motion.
Attachment 269904
Thanks for looking.
Mark
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Are you going to machine a reference edge into your rail mounting bars? That is something THK recommends in their mounting guide.
bob
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Quote:
Originally Posted by
rowbare
Are you going to machine a reference edge into your rail mounting bars? That is something THK recommends in their mounting guide.
bob
I am going to use a ground steel bar bolted on top of the drilled bars pictured above for a reference edge. I only just came across this point and changed the size of the long bars to a wider size to allow room. It seemed easier than trying to machine a 3 foot step in a pre-ground bar.
FYI, there is a great pic of how this works in this installation guide link (Item 2): http://www.rockfordlinearmotion.com/...llation-guide/
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
gt40 are you sure that base and column are big enough? 482mm x 940mm x 203mm at 2,500kgm^-3 is only 230kg (507lb). I think you changed the Y travel to 15"??? This is better than the original 20" of Y travel, but a industrial machine with ~15" of Y travel will weigh 2,000kg+ (4,400lbs+) and still be considered light weight...
You mention your RF45 deflecting too much while cutting steel but how will this machine differ? Your build is obviously early stages but I can't see it being any more rigid than the RF45, and a 10hp spindle will only make matters worse... Getting 20" of travel from 780mm rails leaves only ~250mm carriage spacing (end to end) to support the table / head with.
Am I right in thinking you're expecting the steel plates to remain perfectly flat and parallel even when cast? Or are you going to scrape the plates flat or something once cast?
Sorry if I sound really negative, it seems to me that you haven't planned this out sufficiently. By the time you've finished you'll probably have spent enough to have bought a working used machine, which will be rigid and precise enough to do the work you want without all of the hassle of building the damn thing.
I hope this helps,
Fenza
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Quote:
Originally Posted by
Fenza CNC
gt40 are you sure that base and column are big enough? 482mm x 940mm x 203mm at 2,500kgm^-3 is only 230kg (507lb). I think you changed the Y travel to 15"??? This is better than the original 20" of Y travel, but a industrial machine with ~15" of Y travel will weigh 2,000kg+ (4,400lbs+) and still be considered light weight...
You mention your RF45 deflecting too much while cutting steel but how will this machine differ? Your build is obviously early stages but I can't see it being any more rigid than the RF45, and a 10hp spindle will only make matters worse... Getting 20" of travel from 780mm rails leaves only ~250mm carriage spacing (end to end) to support the table / head with.
Am I right in thinking you're expecting the steel plates to remain perfectly flat and parallel even when cast? Or are you going to scrape the plates flat or something once cast?
Sorry if I sound really negative, it seems to me that you haven't planned this out sufficiently. By the time you've finished you'll probably have spent enough to have bought a working used machine, which will be rigid and precise enough to do the work you want without all of the hassle of building the damn thing.
I hope this helps,
Fenza
I am only 4 years into cnc and it is at the serious hobby stage. I want to make some 3d stuff in limited quantities in steel and I want it to be more accurate than my RF45 clone- these things are the basis for doing this build. In a perfect world, I would have Brother Speedio but as the wife won't sign off on that just yet, this is the current upgrade.
As far as the design, I am trying to keep each major components at 700 lbs / 300 kg. It will also be bolted on a much larger subframe that will add considerably to the mass I expect the full mill with the subframe( still finalizing the design) will be around 2500 lbs/1130 kg. I got all my rails, thk and nsk 32mm ballscrews and basic materials for 2k so far. Add my time and spindle + electronics pneumatic draw bar and I hope to be well under 10k. I think if I can achieve this price point with the components I am using it should be a major step up from my current mill and hard to beat in terms of cutting ability, accuracy compared other mills in this price.
I am still tweaking the vertical column. 11x12x36 is the current dimensions and re enforced with large steel tube cast inside. Should be about 480lb with the steel inside. This is alot better than the 100Lb or so weight of the RF45 column but it could be bigger.
Most important, when I finish, I will know the machine inside and out and be able to maintain and fix it if need be. Modern VMC's can be very complex and expensive to fix and there is the learning curve. I also would rather start with new stuff than learning fix someone elses mess.
To your comparison with an RF45, I am not sure how familiar you are with these machines. The column is 7x9 tapered hollow cast Iron, as is the base. I can pick up and move the column, the base or the table by myself. The whole machine is only around 800 lbs/350 kg without the motor and stand. Going from a RF45 to this build will allow me to replace dovetails with THK linear rails, 3 times the mass and the room to fit proper sized ballscrews and servos.
I am still tweaking the vertical column. 11x12x36 is the current dimensions and re-enforced with large steel tube cast inside. Should be about 480lb with the steel inside. This is alot better than the 100Lb or so weight of the RF45 column but it could be bigger.
You brought up an interesting point on the steel rails. I tested a 1/2"thick piece a foot long cast at the bottom of a box mold placed on a granite surface table. It was dimensionally unchanged. The ground steel will be through bolted to the mold and cast in a horizontal position with the epoxy granite on top in the same manner as my test. We will see for the bigger piece. I guess I will scrape or grout as needed.
For my part, the biggest thing I am trying to work out is mixing 3 - 4 cubic feet of epoxy granite per pour for each section. I have planned for a total of 25 gallons.
Thanks for the challenging questions!
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
In my opinion, 10 hp is too much to expect in a light machine like the one you are building. 5 HP maximum, and even that is pushing the limits of your current design. My recommendation is 3hp especially since you are thinking of doing 3D work, wwhich 90% of the time is done with small cutters or ball mills and at high rpms.
I think you will be pleasantly surprised what you can do with 3hp.
I would concentrate on accuracy and speed of motions and spindle rpm.
Just my thoughts.
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Oh, and one last thing, add a fillet or chamfer on you column where the base attachment points are. At 90degrees you have a weak connection there.
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Quote:
Originally Posted by
G59
In my opinion, 10 hp is too much to expect in a light machine like the one you are building. 5 HP maximum, and even that is pushing the limits of your current design. My recommendation is 3hp especially since you are thinking of doing 3D work, wwhich 90% of the time is done with small cutters or ball mills and at high rpms.
I think you will be pleasantly surprised what you can do with 3hp.
I would concentrate on accuracy and speed of motions and spindle rpm.
Just my thoughts.
Thanks for the suggestions. As far as the spindle size, I am happy to spend less money on a lower HP spindle but I have a 3 HP 8k capability on my RF 45 already and I wish I more power and rigidity. I also converted it to 30 taper with a Pneumatic bar. I will definitely get more than my current 3.
Quote:
Originally Posted by
G59
Oh, and one last thing, add a fillet or chamfer on you column where the base attachment points are. At 90degrees you have a weak connection there.
Yeah, I did the cad sketch to layout things in relation to each other and it doesn't really have all the fine details. I understand about putting chamfers on corners like you said. Actual mold will have that on all internal corners too because it is easier to release from the mold as well as stronger.
Really appreciate the suggestions- keep them coming.
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
We'll good luck anyways. It's an interesting build and I look forward to the results.
for comparison, my 5hp mill weighs in at 2100kgs and similar work envelope, cast iron.
I'm not familiar with granite so I'll be watching and learning as you go along.
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Out of curiosity, was that 8000rpm spindle driven 1:1 by that motor?
A 3 hp spindle has no problem doing a 0.25" DOC at full WOC, with a 2.5" face mill in 4140. Even less trouble in mild steel.
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2 Attachment(s)
Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Quote:
Originally Posted by
G59
Out of curiosity, was that 8000rpm spindle driven 1:1 by that motor?
A 3 hp spindle has no problem doing a 0.25" DOC at full WOC, with a 2.5" face mill in 4140. Even less trouble in mild steel.
Here is a pic of the motor:
Attachment 270098
Pulley setup:
Attachment 270100
Full build thread is on the zone here:
http://www.cnczone.com/forums/vertic...49951-cnc.html
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Quote:
Originally Posted by
gt40
We'll done on the PM45.
Anxious to see this build progress.
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7 Attachment(s)
Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Update:
Out with the old, in with the new... The ballscrews I was looking at got sold but I found some bigger ones.
I got a 40mm THK ground screw and another ground ballscew for Harding that is a double nut. Both are larger than my original design so everything got supersized.
The new base is 42" by 22 3/4" x 9" deep I was able to get the mold almost ready to cast. All I have to do is drill holes for the ballscrew mounts and a few more for the column mounting.
Here are some pics:
Old base mold next to the new one:
Attachment 270778
Length:
Attachment 270766
Width:
Attachment 270768
THK 40mm ballscrew- this thing is really heavy, new old surplus-. It must weigh 50 lbs/22 kilos:
Attachment 270770
36mm ballscrew for harding machine. It should be arriving next week:
Attachment 270774
Here is a pic of the layout for the mold base. It is almost ready to go- I will be radiusing all corners in the mold with grout. The pipes are going to be cast in place lift points- stick a pipe or lift strap through them. Keep in mind all of these pics are from the perspective of the bottom of the base looking up or upside down:
Attachment 270776
Final shot showing the x axis linear rails laid over the mold to gauge foot print- The wider base will support the x axis better.
Attachment 270764
Thanks for looking
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Looks interesting.
But I am also bit sceptical about the precise ground bars of steel you are going to use for rail support. My personal opinion is that it is waste. It will be quite impossible to set them to such accuracy as to not require machining (grounding) after the epoxy is hardened. Personally I would just use milled bars and then, when the casting is done, let it be machined on one clamping with column plate as to have ortogonality.
Well I will be interested in how you take the build on.
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
The problem with showing a build in progress here, is you will be criticized by a thousand arm chair engineers. This can make you second guess everything to the point of constant changes being made and soon when you run out of patience or money, you end up with nothing.
It's your build. You know the basics of what is needed, so just go with your plan.
A few month back, I too had a vision and when I posted my drawings or model, most criticized it and yes I made many changes to the original plan. In retrospect, all they did was stall my build. I learned. Being an engineer by profession, I stopped updating my models and went solely on my knowledge and experience. Today I can say my build is going well, and when it is complete, I will post how it was done.
I think you are headed in the right direction.
To prove what I mean, how many here know the real reason for having the column bolted down on two footings instead of just one square column with a flange bolted all around.
I think you're doing great.
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Quote:
Originally Posted by
G59
The problem with showing a build in progreas here, is you will be criticized by a thousand arm chair engineers. This can make you second guess everything to the point of constant changes being made and soon when you run out of patience, you end up withnothing
No worries- I am appreciating other perspectives and it makes my design better. The new base is an improvement and supports the x axis better + stronger and 30% more mass. I will grind/grout the rails as necessary to get them perfect. I got the steel cheap on ebay and it adds significantly to strength. I think thick steel bar cast flat should stay such but it should be an interesting observation in any case and I am hopefully starting from a pretty decent place compared to some regular hot rolled steel. I had to order extra epoxy however :P
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
One of the tags in this thread is tormach. Do you plan to use a tormach head?
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Quote:
Originally Posted by
nateman_doo
One of the tags in this thread is tormach. Do you plan to use a tormach head?
I am not using a Tormach head. No idea how this tag got in here :P I am looking at 5- 7.5 hp 10k spindles
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Cool build. are you going to use a commercial aggregate, or make up your own?
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Quote:
Originally Posted by
RotarySMP
Cool build. are you going to use a commercial aggregate, or make up your own?
Thanks for the interest. I have 12 gallons of epoxy so I guess I will be rolling my own. I would be open to a cost effective commercial mix but I wasn't aware of any
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
12 gallons?????
what is the epoxy to aggregate ratio???
that seems like alot since the epoxy is supposed to be the binder only, and not the actual structur. Something is wrong here.
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Hi Mark,
Epuself is the only premix option that I am aware of
Do-it-yourself Materials:
Their main business is manufacture of polymer concrete machine beds for third party vendors. If you haven't seen the videos yet, you might find some interesting details...
https://www.youtube.com/user/EPUCRET?spfreload=10
Quote:
Originally Posted by
G59
To prove what I mean, how many here know the real reason for having the column bolted down on two footings instead of just one square column with a flange bolted all around.
I would be interested to hear the benefits of the split column design?
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
The biggest benefit of a split column design, is the reduction of vibrations being transferred from the column, to the base. If we'll implemented, it can even cancel them out. It however has its own disadvantages.
The biggest one is it adds to the complexity of your molds for both the column and the base. It is also less rigid then an all sides flanged column of the same size. However if properly engineered, it can achieve the same performance.
Vibration travelling through the column are split in two thereby reducing there amplitude in half which are then, disippated through the base as two waves and when they collide with each other towards the centre, most will have cancelled each other out.
make any sense to you?
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Quote:
Originally Posted by
G59
12 gallons?????
what is the epoxy to aggregate ratio???
that seems like alot since the epoxy is supposed to be the binder only, and not the actual structur. Something is wrong here.
Well, the base alone is going to 650 lbs/295 kg. 12% of that is 78 lbs/35.3kg worth of epoxy assuming a gallon is about 9 lb/4kgs.
Maybe I can get to 8-10% epoxy to aggregate but figure some loss from mixing it and transferring it between containers. I have worked with carbon and fiberglass composites and figure it is good to have a bit extra.
Heh, maybe I am too tired from my day job as a portfolio manager- It is possible to fail math in the afternoon after getting up at 430am every day for years...
Voyager- thanks for sharing on the EPUSELF. Any idea on the pricing and if it is available in the states?
On a final note, I had a detailed conversation with DMM Tech about servos. I have had great success using their 750watt servos on the RF45 clone mill and 400 watt on the 13x40 jet lathe. Going with 1.3kw all around with the 16 bit encoders and new drives. They have provided me really good support on both builds and the price is right + I have 3 years of hard use on the mill with no issues. This thing should fly with the jumbo ballscrews and servos...
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
In Europe I know of Silimix 282, and Sikadur as Fuller curve pre graded aggregates. Sikadur is a only sold with it's epoxy, silimix as dry aggregate.
For me Sikadur is too expensive, and silimix would be okay, but the shipping from Germany makes it prohibitive. I am currently experimenting with a self graded aggregate (I posted the recipe in the big E/G thread last week). For the first test piece I used 10% epoxy. Next test will have 8%.
Any idea what that EPUSELF costs?
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Quote:
Originally Posted by
RotarySMP
In Europe I know of Silimix 282, and Sikadur as Fuller curve pre graded aggregates. Sikadur is a only sold with it's epoxy, silimix as dry aggregate.
For me Sikadur is too expensive, and silimix would be okay, but the shipping from Germany makes it prohibitive. I am currently experimenting with a self graded aggregate (I posted the recipe in the big E/G thread last week). For the first test piece I used 10% epoxy. Next test will have 8%.
Any idea what that EPUSELF costs?
If I remenber correct I think it was EURo 2.5 / kg delivered to Denmark. EPUSELF is good product and very easy to use. I have only had good results with it. And also the help and support from EPUCRET is very good.
Jacob
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Anyone have any thoughts about a USA version of the EPUSELF concept?
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
I believe EPUSELF is targeting small scale production without dedicated tools such as vibration tables or elaborate mixers. I have heard their solution has a higher epoxy percentage to make the casting process easier. Sorry, don't know the cost or availability in the US. However Rampf is present in the American market and a quick phone call could get you answers.
RAMPF Group, Inc.
49037 Wixom Tech Drive Wixom, Mi 48393, USA
T: +1 (248) 295 0223
F: +1 (248) 295 0224
RAMPF USA | Reactive resins, dispensing equipment, tooling products:
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Voyager77, you are right. EPUSELF comes in pre-measured bins with the aggregates and the resin. The bin can be used to mix the polymer concrete in by just stirring with a mixer. The epoxy percentage is higher than in their professional services concretes to make it easier to mix and increase flowability. This makes the EPUSELF a little bit weaker than the professional concretes, but not by much.
I am not associated with Rampf. Just a happy customer.
Best
Jacob
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Voyager77 and Jacob, thanks very much for the information. I've sent an email to RAMPF in the USA and will let everyone know what I get for a response..
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1 Attachment(s)
Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Update:
I have the mold for the base almost finished and the ground steel bases for the linear rails aligned and bolted to the mold. The two 1/2" thick 3" wide bars also have the benefit of supporting and keeping the mold really flat. Pic of the mold with the ground steel bars bolted and aligned:
Attachment 271942
My epoxy just arrived and I should have the "flour" portion of the aggregate mix tomorrow.
FYI, the "flour" is from a pottery supply house and is Custer Feldspar, so names because it is a type of mineral mined in Custer, SD, is made up of silica and alumina combined with sodium and potassium oxides, It is finer than their 320 grit stuff they had and the price was right at 50 bucks shipped for 55lbs.
I have 3 size sands, decomposed granite to pea sized gravel also.
I plan on casting next week now that I have everything together.
Thanks for looking
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7 Attachment(s)
Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
I picked up a 1000 lbs of aggregates and sand and rinsed about 300lbs of the larger sizes. I was able source everything local to avoid shipping costs but the "flour" portion made up of powdered quartz and alumina- I got that online from the big ceramic store 50lbs for 50 bucks including shipping. FYI, it really does feel and look like fine flour. Everything else came from Home Depot and the local West LA Building Supply store.
On top of that, the epoxy came:
Attachment 272632
Supplies:
Decomposed granite, 60 grit sand, small pebbles and a giant 90 gallon mixing tray:
Attachment 272630
Unloaded:
Each sand bag is 100 lbs and the rest are 50 or 75lbs + more in the garage
Attachment 272634
I am easily amused but the mixing tub really is awesome- you can mix the whole batch in one shot.
Attachment 272636
Here are the different aggregates:
Attachment 272638
To promote adhesion, you need to wash them and let them dry properly. The decomposed granite was really dirty:
Attachment 272640
30 and 60 grit sand also- I didn't have to wash that because you can buy graded washed and kiln dried fairly cheap in 100 lb bags.
Here is a close of the mineral "flour"
Attachment 272642
Well, my arms are sore but I hope to be able to pour the mold this weekend if I can get the rest of the aggregate washed and dried...
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Cool, this is about the same set of sizes as I have except you have one size larger pebbles. What recipe are you using to approach the Fuller curve? I am using Thomas Zietz's XLS with a 0.4 grading increment, plus 8% epoxy, and have about 50GPa young's modulus (7.c x10^6 psi)
Mark
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Re: Mark's EPOXY Granite 18"x20"x20" (700mmx780mmx780mm) vertical mill build
Quote:
Originally Posted by
gt40
... but the "flour" portion made up of powdered quartz and alumina- I got that online from the big ceramic store 50lbs for 50 bucks including shipping.
Mark,
Was this the "flour" you used ... Laguna Silica, 200 Mesh in Bulk ...
I am in search of "flour" locally and need to have something as an example as "quartz flour" is getting the deer-in-the-headlights look when I ask about it.
Thanks,
Arvid