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Cutting 4130 sheet is a pain

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wbpace

Well-Known Member
Joined
Aug 31, 2007
Messages
320
Location
Escondido, CA
I'm having a heck of a time finding a good way to cut my 4130 sheet. First off, my bandsaw is a small electronic DC motor type that will only go down to 300 fpm, which everyone says is too fast. I can't use the wheel replacement tricks to slow it further. Forget the die grinder, it's too crude. Saber saw - pthhh. And I just don't look forward to the armstrong method with a hacksaw or tin snips. So I'm looking for alternatives to using a hacksaw or tin snips for at least most of my cutting. At least once I get the blanks cut out, grinding/sanding them will be easy enough.

Earl Luce has a Hints for Homebuilders tip where he uses an old paper cutter as a metal shear (see http://www.eaavideo.org/video.aspx?v=595056135001). In the video he just cuts thin aluminum and plastic, but has anyone tried this on .035 4130 sheet? It seems like a nice way to go for cutting at least most of the flat stock I have to go through. It would be especially good for making the 80 or so tabs that are needed.

Any other ideas?

O'Bill
 
Bill, how you doin?

035 cuts good with aviation shears, the heavier stuff I find works best with a grinder and cutoff wheel.

Show us your progress!!!

I have not got much done on the fuselage in the last month or so as I am working on a "top secret" project. Hope to get done with this project soon so I can get back to the fuselage.

Bryan
 
Hey Bryan,

I finished my own "top secret" project in mid-December. Since then I finished tacking up the fuselage and I am getting it ready to put it on the rotisserie. The last month has been slow as most of my building time has been spent practicing my welding (I'll make another post about THAT experience soon). In the meantime, until I am ready to actually begin welding, I want to start making on these small pieces when I am not practicing.

O'Bill
 
Well I am building a cnc plasma cutter not just to make sonerai parts but for other uses as well, perhaps you can find someone local to cnc cut the various parts for you? Not everything has to be hacked out with basic tools, at least I don't think so. Maybe when I am done with my cnc I can help the community out but it's a few month out right now.
 
I took Scott P's advice and shelled out $200 for a Harbor Freight metal cutting band saw. It has trouble keeping the blade on the pulleys now days, but it served well for a few years making all the Sonerai parts and several other projects, too. Can't have too many tools!
Scott
 
For cutting sheet metal nothing beats a pneumatic nibbler from ATS. Its too easy! In fact, if you don't practice first you will make a mess of it because its so darn fast. Like 6 feet per minute fast.

With a few minutes of practice you are almost drawing the shape you want. Its effortless and you can get very detailed with it. With a few hours practice you can make things that look really pro.

If you take a straight edged ruler and clamp it to the piece you are cutting you can make perfect straight edges. If you have a piece you want to duplicate you clamp it to the top of the sheet and use the edge of the original as a guide to replicate the piece.

A common trick is to cut the shape you want in metal out of thick plastic, cardboard or my favorite, thin hobbyshop plywood. Lay the template on top of the metal. Use the edge of the template as the guide and follow it around for a nearly perfect reproduction.

That is how I intend to do the tail ribs and full size cutouts from the plans.

The only problem is the 18 guage max thickness... Makes me cry sometimes :p

I am trying to save my pennies for a nibbler that does tubing. That is the perfect way to cope tube. Use the pattern method above and you are nearly perfect each time.

The nibbler is my second favorite tool. My Meco Midget is my favorite... If only I was any good with the darn thing ;-)
 
I think I may have found a solution that works for me. At first I struggled with the idea of dropping 200 bucks for a Harbor Freight metal bandsaw, but really, I already own a bandsaw. It just won't run slow enough for cutting steel, and since it uses an electronically controlled direct drive DC motor, replacing the pulley to slow it further is difficult at best. But it does everything else I need, so I was having a hard time crossing that Rubicon.

Then I found some very thin (3/64" thick x 4" diameter) cutoff wheels at Harbor Freight, 10 for $9. And then I came across this small dry tile saw on sale for 40 bucks. It seemed a match made in heaven, so I tried it and it works like a charm. Of course, I could have just used my grinder with the wheels, but the circular saw makes it much less tiring to hold, is more controllable, permits using a fence to cut straight lines (think of those 80 or so tabs that must be cut), and boy is it FAST!

Here's some pictures of the saw & wheels, and an example of the really narrow kerf it cuts (the vertical "line" in the center of the plate. It literally took only 5 seconds to cut that slot.

Total investment was $55 with tax, and I can even use that saw when I tile the family room floor next month. I am now a happy camper.

O'Bill
 

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Since my last post on this thread, what little time I have had to work on the Sonerai these past few months have been spent on welding the fuselage, and I basically haven't gone back to cutting the steel sheet since. The dry tile saw/cutting wheel approach worked fairly well, but I found that I wasn't really enjoying all the cutting and grinding.

It now so happens that my yearly parts pilgrimage is coming up soon (also known as the Aircraft Spruce Customer Appreciation Day and it's usual 15% discount on almost everything) where I stock up for the next years building. I am looking for a quicker, albeit more expensive way to get this done to help make move things along, and if I need to buy more steel, this would be the time.

So the questions are: What should I expect to pay to get all of these parts laser cut? What about using waterjet cutting instead? Would that be cheaper (or acceptable)?

O'Bill
 
Hi Bill,

I have an Amada laser. If you were in South Africa, I'd cut it one evening for you.

The pricing structure varies from shop to shop, but we work on material cost X 2.5

That should give you a rough idea.
 
Unless you make the cad files for the parts the vendor will also charge you for cad time, at least in my area they will. Most shops in my area expect you to have usable data for programming cnc machines.
 
Bob,

That sounds fantastic! Are they compatible with TurboCad? I bought a copy sometime back but never learned to use it. I have some background in CAD from many, many years ago, so I can probably figure it out well enough to add any missing parts if I had something to start from.

I'll send a PM with my email address.

O'Bill
 
I had some small pieces I needed cut from 4130. They quoted total of $70'ish and ended up charging me $43 and gave me the rest of the 4130 that they ordered to do the job. Depends on the shop, but I paid about 150% of the cost of the material.
 
Bob,

Do you still have those drawings? I'd love to have them to get a quote. I tried sending you my email (wbpace at aol dot com) by PM sometime back, but you may not have received it.

O'Bill
 
Hi O'Bill,

My apologies for the delay.
I have just emailed the files now.

The parts were nested in their respective sheets, and were drawn from the plans for a stock build.
Consideration was made to the grain direction of the material.

A PDF file or two was also attached to help explain things a little.

Please let me know if you have any queries.

Best regards, Byron.
 
Thanks, Bob. I got it and was able to open it with my copy of TurboCad. It seems there is not as much commonality with S-II parts as I would have imagined. There's several things in there I don't recognize, but it does give me a decent jump off point to start drawing the rest.

Only problem is I don't know how to use TurboCad, so I guess now's the time to learn! :)

Thanks again for sharing this with me.

O'Bill
 
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