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

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 ?

Because he can??? :D

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.:D

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.

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'

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.

Thanks for sharing.

Good stuff.

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.

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.

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.

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.

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.

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.

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.

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.

Good to hear you are making progress.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Couple of strips of 50 mm wide double sided box tape to hold it down once done pull pull it of.

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.

you can use small holes. and a small cutting tool. like 3mm or so.
but in this video you can see it work.
if you going to make small pieces do more and smaller holes.

https://www.youtube.com/watch?v=fOrkvPF0pro

i use something like this on thin sheets of wood. with a 1200w vacuum cleaner motor.

Been a while since I have posted, so a quick update.

The tests with cutting any kind of sheet metal were a total failure. For thin sheets, I had problems with the material lifting up off the vacuum table, snagging and breaking the bit. I was also unable to cut even 1/8" sheet. In that case, there was so much chatter that I broke bits. So for now there will be no metal cutting with this machine.

However using the machine as a pen plotter and for cutting wood, I have no complaints. Being able to plot directly onto the aluminum is much faster than doing manual layout.

I finally got electrical in my bigger shop building and moved the mechmate to its new home last week. This gives me the space to finally start working on a proper dust collection system for the machine. Chasing the cutter head around with a shop vac gets rather tedious.

The plan for the vacuum is to buy a Harbor Freight dust collector as a base, add a Dust Deputy for chip separation and a Wynn filter on the exhaust.

dbinokc,

I have cut 0.05" bendable Aluminum on a regular basis on my machine using an 1/8" bit without hold down. I use an upcut spiral O Flute all the time at 50 IPM. So it can be done. I have also cut 0.125" regular Aluminum also.

You have to experiment and try different bits and speeds.

DB don't get too frustrated cutting aluminum can be done whether 0.032 or 0.500 I've done them both with success using 1/8" o-flute 5/32 spiral and 1/4" o-flute. Chip load calculations should be between .003 and .005 and use lubricant. Once you get the chip load close start fine tuning up or down with the feed rates or spindle speed to find what works best for you. I found a faster feed rate and slightly slower spindle speed (heavier chip load) worked best with larger bits, but the target chip load is the same.

Feed Rate/ # of Flutes X Spindle RPM = Chip Load

I also say dont give up. I have cut .032, .041, .020 with no problems also with a 1/8th O-flute. The aluminum I usually use comes with a protective covering on it that I spray adhesive down to a 3/4 MDF.

I would like to try cutting aluminum again, but after destroying some rather expensive bits I am not keen to try again until I have a good plan on how make sure no more bits get broken. Next I try though, I will test with some cheaper HSS!

Dont waste your time with HSS, it doesnt work with Ally, gums up far too easily, the best cutters for aluminium are the spiral O cutters, and even though some have said that a cutting fluid is not needed, I have found that it is essential. If you can rig up a mist cooling system (Noga sells a very good one) that will make the world of difference.

Dust collectors and dies
 

Been a while since I have updated. I finally got a proper dust collection system on my mechmate. No more chasing the bit around with a vacuum. I used a harbor freight dust collector as the base and added a wynn filter.

My first project with the new dust collector added was to make a set of dies for making hat stiffeners for the spar web on my plane. It was nice to stand there and watch the machine work without having to manually vacuum up the wood dust. I also setup a remote webcam so I could keep any eye on progress of the cut from inside the house while doing other things.

Aluminum cutting and Mist Cooling
 

After a long time I decided to try cutting aluminum again. I bought a pack of 10 cheap 1/8" mills. After a bit of experimenting and 5 broken bits later I was about to get a feed and speed that threw some nice chips when cutting 1/8" aluminum. I sprayed the bit with wd40 as it went along.

There was mention a few posts back about using a mist coolant system. How much of a mess is that going to make? I really do not want to coat everything the shop with oil.

it doesn't make that big of a mess when you use a fine tip to deliver the spray and a water borne coolant.