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  #361  
Old Wed 04 June 2014, 18:01
dbinokc
Just call me: DB #118
 
Oklahoma
United States of America
DIY cable chain option

For someone who wants to make their own cable chain might want to consider doing something like what is described at
http://makerplane.org/?p=1753
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  #362  
Old Thu 05 June 2014, 01:56
Fox
Just call me: Fox
 
Amsterdam
Netherlands
aw... that's an awfull solution imo and one thing I would not spend my time on.
Why if you spend all that money on alu profiles en spindle to build a nice machine bother with diy energy chain and not just buy some chinese cheap versions, or even some light used second hand ones if you don't want to pay the big bucks for IGUS et ?
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  #363  
Old Thu 05 June 2014, 03:01
KenC
Just call me: Ken
 
Klang
Malaysia
Because he can???
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  #364  
Old Thu 05 June 2014, 05:33
lonestaral
Just call me: Al #114
 
Isarn
Thailand
Send a message via Skype™ to lonestaral
The cable chain may be cheap and cheerful but it shows you what the human mind can come up with.

An instructor of mine once said to me 'Imagine that you are on a desert island, all you have to work with is what you can find around you and what is in your head.'

That saying has served me well.

Now can I find a use for this bicycle pump and an old rice cooker.
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  #365  
Old Thu 05 June 2014, 05:37
darren salyer
Just call me: Darren #101
 
Wentzville mo
United States of America
Was anyone her ea fan of the old TV show "Junkyard Wars" where teams were pitted against one another in a junkyard and had to build things like hovercraft from what was on hand? It was kinda staged, but I loved some of the ingenuity portrayed.
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  #366  
Old Thu 05 June 2014, 06:16
lonestaral
Just call me: Al #114
 
Isarn
Thailand
Send a message via Skype™ to lonestaral
I think it was called 'Scrapyard challenge' in the U.K.

There also was 'The great egg race' on the T.V. in the 70's, 80'
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  #367  
Old Sun 22 June 2014, 18:25
dbinokc
Just call me: DB #118
 
Oklahoma
United States of America
Cutting Wing Rib Forms

Over the last few weeks I have been focused on the wing spars for my plane. Beyond cutting some spacers, I have not used the mechmate for a few weeks.

While waiting on new drill press, I decided to get started on cutting some of the wing ribs. Specifically the nose rib and the inner most wing rib, which is the largest.

The forms will need a little more post processing before I can use them to hammer out the aluminum ribs. I have to add a 1/8inch radius to the edge ,about a 15 degree bevel for springback and notches along the edges for fluting. Some of this could be done on the machine, but it is just as easy to do this part by hand.

I would have cut some aluminum, but I discovered that new O-flute bit I got a few weeks ago has a 1/8 inch shank and I did not have a corresponding collet. So that is on order as well.

Up to this point, the parts I have worked on the plane with have been relatively small. I did not fully appreciate the size of the ribs until they were actually cut. Glad I can let the machine cut these out for me.
Attached Images
File Type: jpg IMG_20140622_190757.jpg (77.7 KB, 913 views)
File Type: jpg IMG_20140622_190656.jpg (74.0 KB, 917 views)
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  #368  
Old Sun 22 June 2014, 21:26
pblackburn
Just call me: Pete #98
 
South-Central Pennsylvania
United States of America
Thanks for sharing.
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  #369  
Old Mon 23 June 2014, 05:35
darren salyer
Just call me: Darren #101
 
Wentzville mo
United States of America
Good stuff.
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  #370  
Old Sat 28 June 2014, 18:46
dbinokc
Just call me: DB #118
 
Oklahoma
United States of America
More Aluminum cutting tests. Fail

Did some more tests with trying to cut .025 sheet aluminum

Unfortunately this just resulted in breaking my new 1/8 inch down spiral O-flute bit when the sheet metal shifted white trying to do a cut. I was using tape around the edges to hold it down.

I think I am going to have to make a vacuum fixture to really be able to secure the aluminum sheet properly. Even before the bit broke, the cutting just did not sound right. Way too much vibration. The performance just felt sloppy.

I did another pair of rib forms and they came out beautifully. I am confident enough in the machine performance with plywood to go ahead and start cutting multiples instead of one at a time like I have done so far.
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  #371  
Old Sun 29 June 2014, 06:19
Alan_c
Just call me: Alan (#11)
 
Cape Town (Western Cape)
South Africa
Send a message via Skype™ to Alan_c
I have always used small screws to secure the ally sheet to the base board, tape on the edges will never be firm enough to hold it still as it cuts, Vacuum hold down can work but you need a very strong unit to maintain vacuum as you cut through the ally.
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  #372  
Old Mon 30 June 2014, 09:09
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
Ditto Alan.
All the aluminum sheet or billet that I have cut in the past had a mechanical fastener (or machinist vise) attaching it to the table.
The vibration translated to the alum sheet always broke my bits if I allowed it to move.
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  #373  
Old Mon 30 June 2014, 09:47
dbinokc
Just call me: DB #118
 
Oklahoma
United States of America
For thicker pieces of Al I can see using screws or clamps. Not so sure about Al .040 and under. The plan at this point is to build a 2x4 foot vacuum fixture. This will be large enough to handle most of the sheet metal cutting I would need to do as well as keep the size manageable.
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  #374  
Old Sun 06 July 2014, 16:55
dbinokc
Just call me: DB #118
 
Oklahoma
United States of America
Big Disappointment

Got around to cutting some wing ribs over the long weekend. I ran out of plywood and had to run into town to get some more. I also picked up some MDF to make a vacuum fixture to cut my aluminum sheet with. I plan on doing either 24" or 30" by 48"

My big disappointment came with the drill press I had ordered. I had decided to get a Jet JDP-20MF. Jet is supposedly a good brand and I wanted something that I thought would be built to higher standards than something from Harbor Freight.
The pic of the problem is below. It is the mounting bracket for the table. It looks like some ape on the assembly line tried to force a poorly fitting bracket and cranked the bolt down so hard it cracked the casting! I spend almost double the price of what I would have paid to HF and this is what I get sent. Very disappointing.

Jet's support has been contacted and I will find out this week if their support is as good as I have read. If I get too much hassle from them, I will just box it all up and send it back.
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File Type: jpg damage_small.jpg (128.0 KB, 706 views)
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  #375  
Old Sun 06 July 2014, 17:14
ger21
Just call me: Ger
 
Detroit, MI
United States of America
There are very few tools under $3000 that are as good as they were 15 years ago.
Unfortunately, paying double HF's price is still a very cheap tool, and with tools, you get what you pay for.
Having said that, you really just got unlucky, and probably got the 1 bad one out of 100.
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  #376  
Old Mon 07 July 2014, 04:52
MetalHead
Just call me: Mike
 
Columbiana AL
United States of America
I think Jet will take care of you on that issue. I buy tools from Grizzly (grizzly.com) a lot and once got a lathe that was destroyed in shipping. I refused it and they sent me another one no questions asked. I know a lot of this stuff is made cheap, but Jet, Grizzly and Northern tool has stepped up the quality over the last few years.
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  #377  
Old Sat 12 July 2014, 23:16
dbinokc
Just call me: DB #118
 
Oklahoma
United States of America
All the rib forms have been cut now. I spent the day verifying dimensions. What made it a little tricky was getting a good reference line to take my measurements from. I just do not trust the pen plotters I have to be stable enough to draw reference lines for me. I used some holes drilled using the mechmate to establish a base line. Between direct measurements and comparison of plots made on my architectural printer, I satisfied myself that the rib forms were in spec. The next step is to round over the edges to 1/8" radius, bevel for spring back and add in fluting slots.

The replacement drill press bracket is on order. Since I did not order directly from Jet, I had to go through the seller(Home Depot) to get the replacement. The replacement part should arrive sometime next week. I ordered through Home Depot, because I could have the drill press delivered there. I did not want a semi showing up on my doorstep to deliver.

If the replacement bracket arrives in time, I will move on to drilling the spars otherwise I will move on to making the vacuum fixture.
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  #378  
Old Sun 13 July 2014, 07:02
darren salyer
Just call me: Darren #101
 
Wentzville mo
United States of America
Good to hear you are making progress.
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  #379  
Old Sun 17 August 2014, 19:24
dbinokc
Just call me: DB #118
 
Oklahoma
United States of America
Starting Vacuum Fixture

Been a little bit since my last post, so an update.

After numerous delays, I was finally able to do the match drilling of the spar doublers for my wing. Those are in the background of the picture below.

In the foreground are the stack of rib forms I cut with the Mechmate. After cutting, I still went back in verified all dimensions with the plans. For the most part everything was good. I did sand a little here and there just to fine tune things, but the ribs could have been used without any changes.

After getting my replacement bracket for the drill press, I am happy to report that the drill press runs beautifully. Way better than old drill press I had.

A big delay was trying to figure out how to put together some kind of scaffolding to get a surface to put 12 foot long pieces of aluminum barstock on and be at drill press table height. I finally settled on a combination of a saw horse and then using some 80/20 stock to add something looking like a goal post that I would rest a 2x6 on. I will also use this setup when I do my final match drilling of the spars.

The next step is to make the vacuum fixture for cutting the aluminum sheet. I ordered a LH6765-13 vacuum motor from central vacuum. It is a 120V motor. I also cut down the 3/4" mdf sheet I will use for the fixture. The dimension will be 32"x48". Bascially enough to get 3 sheets from one 4x8 sheet. The main issue was just to keep the size and weight down to a manageable size.

The one question I have is what grid spacing should I use for the base. The thought at this point is to cut slots with a 1/4" bit and 1/4" depth. I thinking 1" squares. This would give essentially give a pitch of 1 1/4". Does that sound right or should I do something different.
Attached Images
File Type: jpg stack_of_ribs_small.jpg (116.8 KB, 509 views)
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  #380  
Old Mon 18 August 2014, 06:38
darren salyer
Just call me: Darren #101
 
Wentzville mo
United States of America
I used a 1/2" bit with a 1" square left intact.
Basically, I drew a grid with lines 1.5" apart, and machined on the line in both directions.
My plan is to replace the worn out top today. Have a couple jobs to get out the door.
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  #381  
Old Sun 21 September 2014, 08:27
dbinokc
Just call me: DB #118
 
Oklahoma
United States of America
Initial Vacuum Fixture Testing

I finally made a few initial hold down tests of the vacuum fixture Pic below.
I did not want to bore any holes through my table, so I decided to do a side port.


Hold down as far as resisting side to side motion is very good.
However if I lift up from the edge, the piece will come right off. Is that
typical for this type of fixture?

My concern is with the thin aluminum sheet I would be cutting. If there is some lift up where the cutting occurs, then the hole sheet could break free. Since these are thin sheets, I think I could just stick with a downward cut bit.

It also looks like I would have to have a minimum sheet size to insure I have get enough force to ensure the whole sheet sticks.
Attached Images
File Type: jpg vacuum_fixture.jpg (81.2 KB, 392 views)
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  #382  
Old Sun 21 September 2014, 09:00
servant74
Just call me: Jack
 
Nashville (Tennessee)
United States of America
OK, this is a newbie asking a question.

If the aluminum is to small, how about using some spray adhesive on the back of the sheet (only, not the table too) then stick it down to the sacrificial surface underneath.

Would that be enough hold?

I use this to stick paper patterns on wood before bandsawing, it might be helpful here.
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  #383  
Old Sun 21 September 2014, 09:13
dbinokc
Just call me: DB #118
 
Oklahoma
United States of America
Spray adhesive is a potential option, but leaves a clean up problem. It would probably be my option of last resort.

Most of the thin parts (.016" and .025") are large though. Smaller parts are generally thicker and would not need the vacuum fixture. They are stiff enough against lift that I could use regular hold downs.
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  #384  
Old Sun 21 September 2014, 09:20
Tom Ayres
Just call me: Tom #117
 
Bassett (VA)
United States of America
More vacuum, smaller zones or both. Part of the problem may be the air volume you're trying to move through the small pipes, might not be enough. I think you'll have to continue your experiments.
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  #385  
Old Sun 21 September 2014, 09:24
dbinokc
Just call me: DB #118
 
Oklahoma
United States of America
There are about 20 slots cut to the edge. I just did not have enough barb adapters for all the holes. Unused holes are currently plugged up.
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  #386  
Old Sun 21 September 2014, 11:32
Tom Ayres
Just call me: Tom #117
 
Bassett (VA)
United States of America
I would say unless you have a super powerful vac pump you're going to need to get more volume of air flow by an increase in pipe diameter which should compensate enough. How much more I don't know.
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  #387  
Old Sun 21 September 2014, 15:58
Fox
Just call me: Fox
 
Amsterdam
Netherlands
How far can you swim when breathing trough a straw ? And how quick ?

Ps. I presume the bottom sheet is sealed ? The side suction is far from ideal for even spread of flow.

Last edited by Fox; Sun 21 September 2014 at 16:02..
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  #388  
Old Sun 21 September 2014, 16:14
dbinokc
Just call me: DB #118
 
Oklahoma
United States of America
I guess it would depend on how many straws you are sucking through.
When I get the rest of the barb connections in, there will be 20 straws.

Yes, the bottom is sealed.

The ultimate test is if I can do the cuts I want, but that will wait until I get the rest of the straws installed which will be next weekend.
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  #389  
Old Sun 21 September 2014, 22:53
hennie
Just call me: Hennie #23
 
Roodepoort JHB
South Africa
Couple of strips of 50 mm wide double sided box tape to hold it down once done pull pull it of.
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  #390  
Old Mon 22 September 2014, 02:14
KenC
Just call me: Ken
 
Klang
Malaysia
Vacuum hold down work best on work piece with large area. pressure (& vacuum) work with force/area. the more area you have, the more holding force. if you cut perforation with only 20~30% metal left, it will hot hold down well.
You have to manage your leakages well to stop small pieces from moving.
When I don't cut through, I'll cover as much as the unused plenum with vinyl mat & cellophane tape to the work piece to keep leakage as low as I could manage.
when I do cut through the work piece, I cover the cut portion with another piece of vinyl mat.
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