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Therapy Project

I have a "flatbed" Atlas that was popular in the '60's. I bought it in the '80's and got a lot of tooling with it. My real machinist buddy told me at the time I got a hell of a deal and he could make it do anything but I'm still a hack. I wish I would have paid more attention to his tutoring. (He is gone now) I also have a table top mill/drill that is popular for hacks like me. It does have an R8 spindle but I haven't really done much with it except drill holes. I do fishmouth tubing on my Atlas with a vee block I made adapted to my milling vice using fine pitch roughing mills. I don't make acute angles, mostly perpendicular cuts but its nice and accurate for fuselage cross members. I don't even use lube on the cut as I don't want to clean up the oil mess. I figure a chinese mill bit from Enco for 15 bucks is collateral damage and the cost of doing business. Enough thread drift from me.
 
If I chose one machine to buy it would be as much of a milling machine I could get. By as much as, I mean as close to one of the full size knee mills, Bridgeport, Enco whatever.
Lathes are nice to have but the mill will do so much more such as if you need to true the ends up on bushings, clamp the bush in the collet and a tool bit in the vice. You can turn part of the OD, face an end and bore or ream the part. Then turn the part around and work the other end.
Fishmouthing tubes, use either an endmill or a hole saw in the mill. Digital protractor or the magnetic mount cube for an accurate setup if you know just what the angle needs to be or creep up to the angle bit at a time if needed. Nice thing with this method is you can easily offset the cut if the tube should not be on centerline.
 
I started with hand tools, moved to a 3in1 machine, then CNC mill, CNC lathe, and then added an old Bridgeport mill. I find most of the parts that I make are made on the Bridgeport. I agree with CharlieN that they are very useful machines and used ones are not all that expensive.
 
I can only dream of CNC but for production or repeatable items they are priceless. We have a company in town that rents time on their machines but you need to have your design on a thumb drive. Getting design from my head to a digital representation is a challenge for me.
 
I ocasionally get frustrated on my mill when I just can not easily achieve the contours that I want and either need to simplify the part or do handwork to get the curves. I look into doing a conversion on my good machine to CNC but soon realize how much that restricts me from what I truly use the machine daily for, making simple cuts accurately. If I tighten up my older mill It would be better than just a good drillpress but I never get around to that.
But I soon have use of a new to the area CNC mill and I have some drawings I am getting ready to send to code.
 
Getting design from my head to a digital representation is a challenge for me.

That is a challenging learning curve to achieve. Back in the mid 80's I took to Autocad quite easily, somehow it seemed natural for me having had proper training in Architectural drafting and my first airplanes had all been drawn on paper. 95% of what I draw now is on 20 YO ACAD software, as in that is what the plane I am currently building is drawn in.
But recently trying to get my mind up to speed in Solidworks is not happening quickly. I had started becoming proficient on Pro-E 20 years back but when that computer broke I could never got that student version running again, it needed it's one version of operating system MS NT3.5 and I never set that up again on a fresh system.
But with EAA's help Soidworks in a good system to draw on.
 
Go back to old-school Charlie

https://youtu.be/mHBanmfn_CA

Glenn

I just looked at a few excerpts, but I think that's pretty much how I do it so far. Except I use dividers to mark curve outer dimensions and I haven't been using a handheld grinder.

Like CharlieN mentioned, I have a bench grinder with two different dressed stones. On larger tubes, I freehand cut the profiles close with aviation shears, and then touch up with the grinder.
 
I think one thing I have grown to like when fitting tubes on a mill compared to a radius dressed grinding wheel, I get to watch the cut. This allows me to back out if it looks like I set it up wrong. Tube notchers, at least the ones that use a hole saw offer this but the one I used many years back was not still enough such that the saw was prone to catching. This might or might not be an issue with the thin, small tube were are working with.
There are guillotine- shear type notchers as well but they are all but useless in my opinion.
Granted a milling machine is a major investment but for what were are working with the small mills should be fine as well as a really good vice on a serious drill press.
 
I think one thing I have grown to like when fitting tubes on a mill compared to a radius dressed grinding wheel, I get to watch the cut. This allows me to back out if it looks like I set it up wrong. Tube notchers, at least the ones that use a hole saw offer this but the one I used many years back was not still enough such that the saw was prone to catching. This might or might not be an issue with the thin, small tube were are working with.
There are guillotine- shear type notchers as well but they are all but useless in my opinion.
Granted a milling machine is a major investment but for what were are working with the small mills should be fine as well as a really good vice on a serious drill press.

or you can use a lathe as someone on here pointed out years ago using a boring bar holder for the tube and setting angle... just be careful and not go to far and have it curl in the thin part of tube as you finish or it gets exciting quick!!

oh and one of my favorite tools for the mill, great time saver
http://www.edgetechnologyproducts.com/pro-tram-system-01-000-10-000-09-000/
pro_tram_by_edge_technology_bridgeport_milling_machine_angle__08115.1391121124.600.650.png
 
you can also just use your aviation snips to cut thin .035" tube angles, very fast....

I tried that a couple of weeks ago and was surprised how easy and smooth it turned out.

Right now I'm sort of on hold waiting for my big tube order to ship. I checked on the Wag Aero "fuselage kit" and they were talking 8 weeks. I sorted through all the drawings and talked with Wicks, and they are saying 1-2 weeks.

So I'm now in danger of having a touch of free time, letting me search for milling machines, etc. CharlieN, you've almost convinced me to get a decent milling machine first. But I started looking at littlemachineshop.com and might get distracted yet again.

I suppose it's a good thing that I have to pay a bunch of money for licensing fees and business taxes by the end of the month to keep me temporarily out of trouble.
 
So I'm now in danger of having a touch of free time, letting me search for milling machines, etc. CharlieN, you've almost convinced me to get a decent milling machine first. But I started looking at littlemachineshop.com and might get distracted yet again.

you're down in the states, you should be able to find a used mill easy.... or run over to http://www.grizzly.com and pick a new one up
 
I use just about everything mentioned to get the final result. I never use one of the "joint jigger" type hole saw cutters on anything under 1" in diameter. Not a good tool investment if tube fuselages are your main project. Silver pencil and snips work good on .035 wall. I even hog out a cut on .035 with snips sometimes before finishing in my lathe. Here is a cluster that is mostly cut with snips. I have a Harbor Freight "mini" chop saw (6" wheel)that I took the guard off for manual grinding. I hand grind my silver pencil marks and I get accurate results with it.(gloves and eye protection NOT optional) Everybody has their favorites. One luxury I have for the last five years is my wireless foot pedal for my tig. Even though you still have to drag the torch around its great not dealing with a pedal cord when spending a lot of time under the hood on a fuselage.
 

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you're down in the states, you should be able to find a used mill easy.... or run over to http://www.grizzly.com and pick a new one up

Right. So far I’ve found one only 2 hours away—a Simplon horizontal mill, which at $2500 is only about 50 cents a pound!
I’d have to build another wing on the shop, though. And probably rig up a 3 ton gantry to get it out of the truck.

I use just about everything mentioned to get the final result. I never use one of the "joint jigger" type hole saw cutters on anything under 1" in diameter. Not a good tool investment if tube fuselages are your main project. Silver pencil and snips work good on .035 wall.

Well, I’m glad I’m not the only one who is suspicious of a hole saw on .035 tubing. Before plunging into a joint jigger thing, I tried a straight 90 degree cut on some scrap in the drill press. It didn’t look promising. It seemed like, at best, the setup would be more tedious than just drawing lines and cutting or grinding to the lines.

I like your snipped joints. I’ll probably stick with that as the first bit of shaping.
 
In the bicycle world they use tube coping calculator programs to print a paper outline template to wrap around the tube and then a marker to transfer that cut line to the tube. In the programs you enter the diameter of both tubes and the angle of intersection. You then print, cut the paper, follow the cut line with a marker, and then trim the pipe back to the cut line. An example program is http://metalgeek.com/static/cope_custom.pcgi
 
The paper wraparound template can be created with Solidworks also, but I don't know how to do it. BTW, Solidworks is free via EAA membership.
 
In the bicycle world they use tube coping calculator programs to print a paper outline template to wrap around the tube and then a marker to transfer that cut line to the tube. In the programs you enter the diameter of both tubes and the angle of intersection. You then print, cut the paper, follow the cut line with a marker, and then trim the pipe back to the cut line. An example program is http://metalgeek.com/static/cope_custom.pcgi

Yeah, that's a pretty neat program. I've tried it out a bit. I confess to having some initial troubles printing out the outline to scale. I finally got a test 60 degree pattern cut after 10 or 15 minutes. It does leave a nice cut line.

But I'm not completely confident of my paper cutting skills. On scrap I tried out a modification of something I learned long ago, lofting boats: Use dividers to mark a few places and eyeball the curve. The key is to hold the dividers at a consistent angle.

I suppose, if I want to run an efficiency test, I could try doing 10 tubes with the printout approach, and 10 tubes with the eyeball trim and trim some more, and see what works best.

The paper wraparound template can be created with Solidworks also, but I don't know how to do it. BTW, Solidworks is free via EAA membership.

I joined EAA a couple months ago and saw that. I'm not a Luddite, but I'm sort of scared of the potential for rabbit-holing my time. That is a fascinating program!
 
my laser printer prints different sizes, like if you do 3 separate prints or try to rerun a sheet through it might be 1/4" different size.....
 
Wing Planning

As I wait for my fuselage materials order to come in, I started thinking about wings.

Plans call for a wood wing, but state that a PA-18 wing is suitable. I'm drawn to a wood wing after looking at Marty's work on his 2+2, but I'm also intrigued by the possibilities offered by Keller flaps.

I contacted Performance STOL and they pretty much said they don't know if the Keller flaps would be compatible with wood spars and ribs. Pretty much discouraged me from trying.

And, just to add to the mix, I have a friend who owns a commercial forest and mill. He told me he has some extremely nice 20 foot vertical grained douglas fir, no knots, straight grain, 14 rings per inch, etc. He knows I love this kind of wood and would give me first dibs for boats, airplanes, whatever.

I guess the first question is, does anyone know what the weight of a standard aluminum PA-18 spar is so I can compare it to this doug fir?

Second question, should I abandon the Keller flap idea, or go with an aluminum wing?

I'm not really asking you all to decide for me--just laying out the latest swirling thoughts.
 
my laser printer prints different sizes, like if you do 3 separate prints or try to rerun a sheet through it might be 1/4" different size.....

I ran into that, too. Somewhere I found a scale setting for my Officejet printer to match the scale shown on the screen. It always takes me a little bit to remember how to do it.

Now I remember, I ended up taking a copy of an image and putting it into a Word document, and then adjusting the scale of the image to the inches shown in the MSWord program. I made a couple templates that were accurate to 1/64". Not machinist quality, to be sure, but helpful.
 
Plans call for a wood wing, but state that a PA-18 wing is suitable. I'm drawn to a wood wing after looking at Marty's work on his 2+2, but I'm also intrigued by the possibilities offered by Keller flaps.

I contacted Performance STOL and they pretty much said they don't know if the Keller flaps would be compatible with wood spars and ribs. Pretty much discouraged me from trying.

Second question, should I abandon the Keller flap idea, or go with an aluminum wing?
Years ago I helped a friend get an STC to install flaps on his wooden spar J-3/PA-11. This was approved at the Birchwood Airport by Gordon Mandel of the Anchorage FAA engineering. I don't recall if there were any differences from the metal spar PA-18. I would suggest that as long as the spar is properly supported at each hinge location that it would be satisfactory.

If you want to get the airplane records from the FAA, I think that I may be able to find the N number. The plane has since been destroyed.
 
Years ago I helped a friend get an STC to install flaps on his wooden spar J-3/PA-11. This was approved at the Birchwood Airport by Gordon Mandel of the Anchorage FAA engineering. I don't recall if there were any differences from the metal spar PA-18. I would suggest that as long as the spar is properly supported at each hinge location that it would be satisfactory.

If you want to get the airplane records from the FAA, I think that I may be able to find the N number. The plane has since been destroyed.

Thanks for the info. The plans allow for an optional set of flaps, so I don't think you need to track down the STC info. I think the Performance STOL concern was that the Keller flaps apply more twisting force than standard flaps.
 
The 2+2 plans show a picture of a flap. Thats all. If you want to see how it can be done check out how Marty did it on his wood spar. The Wag Aero prototype 2+2 was built with PA12 wings.
 
I like wood, I like aluminum too. They both have their merits. I also see no problem with the added load of BIG flaps on the wood spar, just add the needed structure to transfer the twisting load forward to the front spar. I can understand being cautious about adding the flap loads to a factory with that is not designed for the added load, but that is not where you are at.

One note about the Keller flap design, it is optimized to replace the stock Piper flaps which do not go all the way up the the rear spar.
I would keep researching and choose a flap system that utilizes most all the space aft of the spar. If nothing else jumps out then go with the Keller system.
 


Tempting for sure. But I think I'll press on.


I like wood, I like aluminum too. They both have their merits. I also see no problem with the added load of BIG flaps on the wood spar, just add the needed structure to transfer the twisting load forward to the front spar. I can understand being cautious about adding the flap loads to a factory with that is not designed for the added load, but that is not where you are at.

One note about the Keller flap design, it is optimized to replace the stock Piper flaps which do not go all the way up the the rear spar.
I would keep researching and choose a flap system that utilizes most all the space aft of the spar. If nothing else jumps out then go with the Keller system.

Well, that sets the wheels turning. I guess I'm going to dig in a bit more on flap design and wing "beefing up."

One idea I've seen is to have compression members bracing top and bottom of spars instead of just the middle.
 
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