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  #661  
Old Sun 12 February 2012, 11:19
danilom
Just call me: Danilo #64
 
Novi Sad
Serbia
If you do try out the vortex tube for cooling, inform us how it work, I was also looking into it as I found out that some shops are using these and dry cutting to cut on costs of coolant and its recycling.
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  #662  
Old Sun 12 February 2012, 16:56
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Hi Miguel

I use ordinary carbide 2 flute cutters. Had a cutter specifically for alloy but killed it instantly doing my first dry cut test.

Some people use compressed air, just standing there with a gun and giving it a squirt.
After all air is a fluid and it is just as much about moving the heat and chips away as much as lubricating.
Some cutting fluids are oil and water emulsions , the water evaporates when heated and provides the cooling to the parts.

The cooling gun is a great idea as it also extends its use into the plastics and polycarbonates that have a real habit of melting if they are cut too aggressively.

With respect to personal safety, even with the small amount of alloy stuff I have done you quickly get tired of breathing the volatiles comes off the machine when the sprays are being used.
Gave myself a really good headache the other day from breathing the vapour.

The gun seems to be a great idea to replace a misting system, so if you buy one make sure to report back on how they go.
I have seen a price of roughly $280 but expect they might be more expensive here in Australia.

Regards
Ross
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  #663  
Old Sun 12 February 2012, 21:00
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Found the first big down side - very large air requirements.
Only found one model that could run on a three cylinder belt driven compressor.
The link to the model above requires something like 25 CFM

Regards
Ross
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  #664  
Old Mon 13 February 2012, 03:25
Regnar
Just call me: Russell #69
 
Mobile, Alabama
United States of America
Ross, have a look at this site. I have read a few reviews over on Pratical Machinist forum and for the most part they were all positive. The biggest negative seems to be the price. Most of them being machinist just google the patienent number and make one.

http://www.fogbuster.com/

http://www.google.com/patents?vid=US...AJ&output=text

http://www.metalworking.com/dropbox/...Fog_Mister.txt
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  #665  
Old Mon 13 February 2012, 04:01
TechGladiator
Just call me: Miguel #94
 
Randolph, NJ
United States of America
Hey guys.. I ordered a Exair 5215 yesterday for $200 (eBay). I will let you guys know how it works once I get it.
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  #666  
Old Mon 13 February 2012, 05:19
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Hi Russell and Miguel

Russell
Great links for the droplet mister.
The drawings and description are very clear.
Thanks

Miguel
Not sure what sort of air supply you have, but when you get yours let us know how it works and what sort of air supply you used to achieve it.

Generally
From what I understand the adjustable air coolers are very inefficient, that does not make them bad but does up the air requirements somewhat.
The adjustment of the units themselves also will have a big impact on the air flow and temp of the air.
This is referred to as the cold air fraction, very cold air requires lots of hot air going out the hot side of the tube.
This link explains the whole thing very well for others that may be interested.
By no co-incidence this is the supplier I was referring to that made a low flow unit capable of delivering a product that was within the 300 liters per minute maximum airflow I have available.
http://www.stream-tek.com/products/v...ifications.php

One tube can also generate a range of flows and temperatures by using interchangeable vortex generators.
This listing on ebay demonstrates how hot and cold generators and flows can be interchangeable in a kit form using one tube as a basic platform.
http://www.ebay.com.au/itm/290538748...#ht_632wt_1139


How they work - that's up to Miguel

Thanks guys great information.

Regards
Ross
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  #667  
Old Mon 13 February 2012, 09:39
KenC
Just call me: Ken
 
Klang
Malaysia
IMHO, The easiest+cheapest+guaranteed+time tested+no-brainer way for applying coolant is by applying kerosene to the bit with a brush.
**ps, use PPE while doing it.

BTW, you get to watch every cutting moves while doing it
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  #668  
Old Mon 13 February 2012, 10:00
TechGladiator
Just call me: Miguel #94
 
Randolph, NJ
United States of America
@Ken. Make sure you have a couple spare fingers on the shelves..
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  #669  
Old Mon 13 February 2012, 21:03
KenC
Just call me: Ken
 
Klang
Malaysia
Water color paint brush has long handle... Don't worry. the bit won't jump out & bite.
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  #670  
Old Tue 14 February 2012, 03:06
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Ken, a paint brush is certainly a cheaper option
And I am a big fan of watching what is happening if nothing more than to be quick to the EStop especially with alloy.

I bought a $5 can of RP7 with a plastic tube nozzle today, it's also a good cheap solution. You don't even have to dip the brush .
I make up a dam of plastic around the part and it catches most of the chips and coolant.

Hold Down Update
Different day and another revision , driving time is good thinking time.
Definitely going to drill a few though holes on the spoilboard.
Also going to use a hollow 3/8 BSP booker rod to save some more height on the vacuum cups.
I can say without reservation this is getting expensive !!!

Regards
Ross
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  #671  
Old Tue 14 February 2012, 06:41
KenC
Just call me: Ken
 
Klang
Malaysia
What is RP7? sounds like my kind of thing
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  #672  
Old Wed 15 February 2012, 01:33
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Hold down - Three Pieces Done

Hi Ken

selleys-rp7_4ce5bbaa2db00.jpg

It is a heavier oil than most spray oils in a can like WD40.
The colour is tending towards a light engine oil tone rather than clear.
Really nearly anything will do.

I have machined the three assemblies that will give me the three ranges of heights I will require to hold the blank.
These are approx 90mm, 100-110mm and 35-50mm.
All assemblies will bolt onto the table for positioning.

IMG_2567.jpg

Waiting for some more ball joints, 3/8 lock nuts and some M10 half nuts before I can install the assemblies.

Regards
Ross
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  #673  
Old Sun 19 February 2012, 19:08
Red_boards
Just call me: Red #91
 
Melbourne
Australia
I'm following your hold-down journey with interest.

I picked up a burr and mowed some foam with it. It sliced through like butter (especially when I made a mistake with home refs and the bit ran diagonally across the piece!).

It's a small bit - 8.8mm diameter, 45mm long, from memory, so probably too small for a full sized board? My first board was only 300mm long ;-) http://www.cheapesttools.com.au/shopexd.asp?id=8459
I'm still seeking out a big burr. I have a "wood miner" to test that has a 20mm dia and is about 100mm long. But it can only be spun to 10 000rpm (designed for angle grinders).

I'm interested in your locating system. Clamping to stringer fore and aft is common, but problematic is the stringer is curved.
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  #674  
Old Sun 19 February 2012, 20:56
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Hi Red

Sitting here working out how the new script based beta version of boardcad 2.1 works as your post came up.
Jed looked into it the other day so I felt I was trailing behind, haha
Happy to report it seems to produce even better gcode.

Great link for the ball nose cutters - winner on that one.

You don't say how you are generating tool paths (assumming Cut3d as you have said in the past) but I had no problems with a 12 mm end mill and 8.8 is not much smaller.
In the end it just means more passes, closer together (stepover is the generic CNC term).
The length of the cutter will probably be the limiting factor due to the plunge depths to cut the sides, stringer ends or the inside upward curve of the nose on the deck esp. if the router base is still in place.

Some machines used/use the stringer clamps, then came along stringerless blanks and an new senerio was required.
Gripping the stringer ends always struck me as a very effective way to hold the blank, so shame that.
Some code, like boardcad, can also cut the stringer if the code is given the parameters to do so.
My philosophy was to go for broke and ensure I could hold all the blank types, stringered, cut stringered, stringerless and wire cut blanks from blocks.

The design process has been expensive and time consuming.
It is also by no means finished as I have not tested the vacuum cups on the curved striations that the ball nose cutters will leave.
Obviously the bigger the diameter of the cutter and the larger the number of cuts will decrease the height of each striation and improve the available vacuum hold.

Finally, now you have cut some foam, darn noisy hey !!!

Regards
Ross
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  #675  
Old Mon 20 February 2012, 19:05
Red_boards
Just call me: Red #91
 
Melbourne
Australia
I use a shop vac to hoover up the foam dust as the cut progresses (feasible for small models). I emptied the vac (gee there was a lot of white dust). Then I made the mistake of assembling the vac for water suction and switching it on inside the house. Tiny white balls everywhere. blown out the exhaust because the filter wasn't in. I was unpopular with the wife, even after I'd finished washing the kitchen floor and vacuuming the toaster etc.

Advice I got from the Cut 3D forum was for 10% step over for finishing foam with a ball end, but this may result in an excessive number of passes. Trade offs.
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  #676  
Old Mon 20 February 2012, 20:42
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Be Careful about Non Specialist Advice

To give some perspective on this one the CUT3D people have advised you to do something like 650 lengthwise passes to machine the blank per side.
A 10% stepover using an 8.8 mm bullnose will only advance sideways 0.88mm per each board length traverse.

Typically a board will be machined lengthwise with something well under 40 passes.
I have doubled that to about 80 passes and it takes around 15 mins to do that.
At 650 passes the machining time will be something around 2 hours per side.
Production machines like the APS 3000 do the job a bit more roughly using wide stepovers but will do the deck in about 6 minutes and the bottom in 4 minutes.

This is an example of a 66 pass deck cut (50 deck + 2x8 rails).
This could easily be considered over shaping but does it look great.
66 Pass Deck.jpg

What the Cut3D people have completely failed to understand is that the shaped blank is screen sanded as a post CNC shaping process.

Regards
Ross
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  #677  
Old Tue 21 February 2012, 03:26
danilom
Just call me: Danilo #64
 
Novi Sad
Serbia
10% stepover is a standard for ballnose, 7-8% for 3D relief and no sanding. So they gave you good advice but for a wrong surface finish.
Get a larger ballnose (25-50mm)so you can get it fast with small stepover for less final hand work.
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  #678  
Old Tue 21 February 2012, 05:27
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
No fooling you Danilo but I still disagree ... to a degree !!

Part of the truth is we are too cheap to buy the big specialised surfboard carbide cutters, they charge an arm and a leg for them here in Australia.
Red is on to a supplier for a 3/4 inch cutter and I have managed to come up with a 20.637mm cutter.

I can't speak for Red but I have allocated a 20 min maximum window per side to achieve the best possible finish with a reasonable cost cutter.
What this means in practice is the 10% stepover is out the window even with the 20.637mm cutter.

10% of 20.637mm is roughly 2mm per pass. The board above allows 50 or so passes for the top surface and then a further 16 for the outside rails.
That moves me along only about 100mm of the 500mm of top surface of the design.
The required stepover even with my new larger carbide burr will be something like 50%. More if the cycle time needs to go down further.
The largest commercially EPS cutter is 31 mm in diameter.
The large stepovers that are commonly used to achieve realistic production cycle times mentioned are no accident

The advise given to Red was offered in a bubble and did not account for scale.
Read it here at http://www.vectric.com/forum/viewtopic.php?f=12&t=13495.
The models x value is only 376mm, so you can afford the luxury of a tight stepover... but not at full scale.

Regards
Ross

Last edited by Surfcnc; Tue 21 February 2012 at 05:28.. Reason: sign off omitted
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  #679  
Old Tue 21 February 2012, 05:37
TechGladiator
Just call me: Miguel #94
 
Randolph, NJ
United States of America
@Ross; I think you can achieve faster speeds if you get a bigger Piston Pullback Spring and change your catalytic converter. haha. Kidding.

I cant wait until I understand everything you mention on your posting above.. I am going to start some reading and try different things with mine.
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  #680  
Old Tue 21 February 2012, 05:38
danilom
Just call me: Danilo #64
 
Novi Sad
Serbia
Maybe you can find a large diameter drill, the method Sean uses for EPS

http://www.mechmate.com/forums/showt...ght=foam+drill
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  #681  
Old Tue 21 February 2012, 05:50
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Thanks Danilo, missed that one.
A really practical suggestion.

Regards
Ross
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  #682  
Old Tue 21 February 2012, 05:54
danilom
Just call me: Danilo #64
 
Novi Sad
Serbia
Look for a really nice shiny HSS drill as in that size 20-30mm you don't want a bit out of balance at high rpm. It works ok I used it couple of times for some tests
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  #683  
Old Tue 21 February 2012, 06:42
KenC
Just call me: Ken
 
Klang
Malaysia
I don't usually get orders for EPS, but my experience with 50mm ball nose on tropical hardwood & MDF says that 7~8% step over will not produce smooth finish without some sanding... I need 3~4% to do without sanding which take way too much time...
Some times, sanding really is a good idea...
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  #684  
Old Tue 21 February 2012, 19:56
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
For any one interested.
I have posted a small piece of code at http://www.boardcad.com/viewtopic.php?t=1244 that will allow ball nose cutters, flatcutters and STL models of cutters to be easily selected in Boardcad.

Regards
Ross
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  #685  
Old Sat 25 February 2012, 17:08
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
MM Impresses

I had a knock on the door Saturday morning, a builder that I know was standing there with a piece of timber and looking concerned.
He explained he needed a wide sloped transition between two floors and it had to be neater than he could do with his planer, power saw, other available tools, jigs etc.

Sketchup provided me with the part model in minutes and away we went.
He got his part (yet another favour I'm afraid !) and left very impressed with the smooth production of an object he could only imagine an hour earlier.

Thinking the MM needs to make me a sign for the front door "Please Open Wallet before Opening Door" Only Joking

Regards
Ross
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  #686  
Old Sat 25 February 2012, 19:50
jehayes
Just call me: Joe #53
 
Whidbey Island, Washington
United States of America
Ross:

Maybe this is a real newbie question: but how do you go from a sketchup design to the Mach3 code for the MM?
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  #687  
Old Sat 25 February 2012, 20:01
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Hi Joe

The key is to convert the model to an STL file.
http://rhin.crai.archi.fr/rld/plugin_details.php?id=429

Most cam applications will accept an STL import.

Regards
Ross
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  #688  
Old Sat 25 February 2012, 23:09
jehayes
Just call me: Joe #53
 
Whidbey Island, Washington
United States of America
Ross:

Thnx.

Joe
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  #689  
Old Tue 28 February 2012, 02:02
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Mechmate Surfboard Shaping Machine Vacuum Hold Down

Today I installed my hold down system.
The units are all easily removable with just 2 wing nuts and two push fit pneumatic connections each.
There is a third low profile unit (not shown) that completes the system.
The low profile unit is used when shaping the deck (top) of the surfboard blank.

Happy to report it works perfectly, providing strong and precise positioning.
Using my venturi vacuum system and storage tanks, the compressor cycles every 3 minutes to maintain the vacuum.

IMG_2577.jpg

IMG_2578.jpg

IMG_2579.jpg

IMG_2580.jpg

Time to make a new surfboard to celebrate the engineering milestone.

Regards
Ross
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  #690  
Old Tue 28 February 2012, 06:12
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
That is just cool. Truly a clever and duty purpose addition to a specialty MM.
Well done.
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