Waterjetting

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gseiter
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Joined: Wed Jan 31, 2018 10:46 am

Waterjetting

Post by gseiter » Sun Oct 28, 2018 9:14 pm

Has anyone waterjetted the various metal parts? I was thinking of using this for the parts that must be repeated like the control horns, parts of the gear, motor mount attachment fittings and a few other. Additionally is there anyone that has already digitized the drawings and would be willing to share them. Thanks in advance for our help. I just finished putting the fuselage halves together so the various pieces of wood now somewhat resemble an airplane. Gene Seiter

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taildrags
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Re: Waterjetting

Post by taildrags » Sun Oct 28, 2018 9:47 pm

Gene; this is a subject that comes up from time to time, from two different aspects:

1. Numerous people have digitized the metal parts of the Piet for purposes of automating the fabrication of the parts, with various modifications and differences. Most builders agree that there are fittings that can stand some improvement from the plans, and most of those improvements have to do with extending the bolt mounting tabs so they protrude just a little more beyond the fabric skin. There are a lot of places where it's difficult to get a socket or combination wrench on bolts and nuts on fittings that just barely extend beyond the fabric, so builders have identified some of those parts that can benefit from modification.

2. Over the years various people have offered sets of precut metal parts for the Piet, either as a business or else as a group purchase cost-share to help other builders by having multiple sets cut while cutting the set for their own airplane. If I remember correctly, there have been waterjet-cut parts offered "on order" in the past but I don't remember who undertook that venture.

I'm sure there are people who have digitized the parts drawings. I've digitized some of them myself, but only for the purpose of 'assembling' a virtual Air Camper airframe in AutoCAD for my own personal study.

tom kreiner
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Joined: Sat Feb 25, 2017 9:49 am

Re: Waterjetting

Post by tom kreiner » Mon Oct 29, 2018 9:10 pm

A few years ago, I "captured" all of the Pietenpol sheet metal pieces, including simple pieces, and welded brackets using SolidWorks. After all of the Solid models were completed, I took them to a shop I've dealt with in the past, and they made a complete set of Piet metal pieces to prove out the drawings. These "proof" pieces were NOT made using 4130, just some 1020, or whatever they had laying around, as they were not to be flown.

The drawings were something I've spoken with EAA about, and my contacts there reached out to Don Pietenpol, who was not interested in working with me. They also referred me to Doc Mosher, but nothing came of that either... Perhaps I'll offer drawings at Brodhead in the future; not sure yet.

My drawings were made in sets; one was for the Aileron brackets, another for the Jenny landing gear, and yet others for tail feathers. All of these were made using proper orthographic projections rather than the crude sketches put together 90-ish years ago. DO NOT DISS ME WHEN I CALL THEM CRUDE SKETCHES! They have stood the test of time, and while they convey the correct dimensions, etc., they exhibit poor draftsmanship. Orrin Hoopman may very well have been self taught, and I'm NOT dissing him either, simply stating observable facts.

One item missing from all of the original prints, and F&G manual, is the grain direction to be used for the pieces. In case the reader isn't aware, bending with the grain is a NO NO, as it produces micro cracking which can produce failures at a later date. My prints have grain directions shown so the builder can fab the parts properly. I've attached a couple of samples to review.

Saving the original work into .dxf, or .dwg formats would be pretty simple, taking a few hours to make a complete set for the airplane. Question is, would anyone be interested in them? If so, I've thought that the entire set would go for around $120., with a license to be used by only one builder. These might sound expensive, but the files would also come with drawings showing all of the details and notes... and printing cost alone is around $70. Since there are 36 pages, this comes to around $3.30 per page.

Take a look, and please give me some feedback, but remember, I'm not disrespecting either Bernard or Orrin, only stating that the original prints were a mess, and I've cleaned them up adding length to marginal fittings, and edited them extensively.

Finally, to answer Gene's question... Ken Perkins had a relationship with his community college, where he took the Waterjet 101 Classes over 20 times, making and selling waterjetted parts to many on the list. Since he is no longer with us, his pieces are no longer available.
Attachments
TBF9001_AX.PDF
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CJS1001_AX.PDF
(47.97 KiB) Downloaded 87 times

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taildrags
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Re: Waterjetting

Post by taildrags » Mon Oct 29, 2018 10:02 pm

Tom; nice work. If the sample "turnbuckle fitting" is the part I'm thinking about, it is PRECISELY one of the awkward conditions that I've encountered on my airplane. Either (or maybe both... I don't remember) at the top of the forward lift struts and the cabane struts, if you put a bolt through the hole in the fitting with the head up, as is the general recommendation so gravity will hold the part in, you have to have the bolt already inn the hole when you install the fitting because there is no way to insert or extract it once the fitting is in place. If you install the bolt later, it has to go in from the bottom, contrary to good practice, and you need to have the washer and nylock nut in place over the hole as you insert the bolt because there's no other way to do it. Same thing with a couple of places where fork-end turnbuckles are installed using clevis pins, because there is no way to install the clevis pin from the top... you have to install them head-down and then try to get the washer and cotter pin installed in a tight wedge-shaped space.

These old-timey airplanes are too bloomin' hard to build. Next time, I'm just going to pop-rivet an RV together ;o)

ArthurD
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Joined: Tue Jun 26, 2018 2:00 pm

Re: Waterjetting

Post by ArthurD » Tue Oct 30, 2018 12:34 am

Water jet cutting is rather expensive compared to plasma or even laser. Most fabrication shops and steel suppliers have access to cnc plasma tables. Some have laser and/or water jet, places that do granite counter tops often have water jets. If the quote you get for the waterjet is more than you'd like to pay I'd recommend asking about plasma.

tom kreiner
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Joined: Sat Feb 25, 2017 9:49 am

Re: Waterjetting

Post by tom kreiner » Tue Oct 30, 2018 8:03 am

Arthur,

You're right; waterjetting is one of the most expensive metal removal techniques known... which is why Ken Perkins took the Waterjet 101 class multiple times.

The caveat with plasma, is that the edges, and some additional area ( splay) will have something called "plasma slag." Removal of plasma slag requires extreme abrasives - zirconia type - and usually removes quite a bit of material. If I were attempting to cut with plasma, I'd ensure ample cleanup around the edges to allow for cleanup to exact size.

Just my $0.02

Tom

ArthurD
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Re: Waterjetting

Post by ArthurD » Tue Oct 30, 2018 9:15 am

Tom,

On thin plate with the correct settings the dross should be almost nonexistent. I've never seen it adhere well enough to require extreme abrasives to remove, I've removed it from 2" thick plates with a paint scrapper. Plasma cutting by hand can get ugly especially when the operator just guesses at the settings but CNC plasma cutters would not be so ubiquitous if it is as you describe.

EAB4
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Re: Waterjetting

Post by EAB4 » Tue Oct 30, 2018 1:33 pm

I have all the metal fittings/parts for my plane drawn out in the computer. When I need to make a part I print out a template and glue it to the metal and cut it out.
For duplicate parts, I use industrial double-sided tape between the metal blanks and make multiple parts as I would single parts.
I can see having some of the landing gear parts cut because of the thickness of the metal involved, but most of the other parts can be cut by hand just fine.

As far as "digitizing" the parts, with the EAA offering a free version of Solidworks, everybody wants to get on the CAD/3D bandwagon, but pretty much any basic drawing program will allow you to draw out your parts for printed templates or save the files in dxf. or dwg. formats if you want to have them cut.

This is a good site to check if you are interested in having parts cut. You can use their online CAD program or import existing .dxf files.

https://www.emachineshop.com

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Richard Roller
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Location: Olathe, Ks.

Re: Waterjetting

Post by Richard Roller » Tue Oct 30, 2018 5:05 pm

Ken Perkins water jetted the steel parts for several years. He made many sets of them. He would take a water jet course at the local community college (with the senior citizen discount) and cut out multiple sets. Before anyone asks, I don't have his drawings. He had them on USB drive and it wasn't found when he died. I'm not aware of anyone having problems with his parts. The comment on grain direction is correct, you have to be aware of the grain direction.

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Terry Hand
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Re: Waterjetting

Post by Terry Hand » Tue Oct 30, 2018 6:44 pm

Oscar,

I was going to send this in to Pat Weeden for a future Newsletter but this has come up on this forum, so I will post it here AND send it to Pat. This is simply a repeat of a post I wrote on the Pietvair Forum not long ago. I try and exercise my "dual citizenship" on both this and the Pietvair Forum so I hope that this helps -

______________

I was not happy with the horns I was cutting and forming in my shop, so I searched out for a source from which to purchase CNC waterjet cut horns, and only found one source on the Internet -

www.icarusair.net/parts/

I spoke with the guy, Steven Richards (Cell - 806-777-3966), and he seemed very nice. They cut them from .025 Chromoly with the tabs attached. He had a delay in his production, and I wanted .032 chromoly horns (although I am sure that .025 is sufficiently strong). So I went in a different direction.

I had drawn my horns in pdf, and liked mine without the tabs (I plan to do like others and weld in a U-channel instead of bending the tabs.), so, long story short, I sent the pdf file off to a graphic design guy in Bangladesh (posted the job and requirements on fiverr.com), and got the CAD file back 3 days and $20.00 later. Here is the pdf of the finished file. You can see that I was able to fit all 10 horn halves on an 18X18 sheet -

Final_dxf.jpg

Not to drag this thread out, but I then found a guy online that allowed me to drop ship him the metal, he water jet cut the horns from the .dxf file I had made, and shipped them back to me. Here is what I got -

CAD_Horns_cut.jpg

I formed them in my shop, then took them down to my welder, provided him a short piece of 3/4" X 3/4" X 0.49 rectangular tubing (ACS Part #03-12800 with one side cutoff to make it a U-channel that fits perfectly) as well as two 1" X 3" pieces of steel for the aileron horns and he welded them up, as shown below -

CAD_Horns_welded.jpg


I spoke with Darrin at LS Brackets, and said he would do the same deal for anyone else. Here is the contact info for them -

LSBrackets LLC (ATTN: Darrin)
5000 Hunter Rd
Woodward OK 73801

lsbrackets@gmail.com

Phone (580) 334-4257 (I did not call them at this number. I found it on the Web, so it may or may not be correct. They are very responsive by email, though, in my experience. Also, they do not retain client's .dxf files, so you would need to email him the file for him to do the cutting - not a big deal; just an extra step in the process.)

Here is the pricing -

Metal ordered and drop shipped from Aircraft Spruce direct to LS Brackets in OK - $31.61
Waterjet cutting charge ($55.00) and return shipping ($12.50) - $67.50

Screen Shot 2018-08-04 at 11.56.29 AM.png

So, for a hundred bucks you can either have the Icarus Aircraft horns with tabs cut, or mine without. I have attached a link to the CAD file below, in the event you already have access to a CNC machine where you live. Feel free to download the file by clicking on the link below and use it. I would caution you about laser cutting these, as it hardens the edges and makes it harder to weld, or so I am told.

https://drive.google.com/open?id=1Dvc10 ... 1ao1C8laLP

You probably are thinking, "Terry, why did you go through all this just to get your horns cut?" I would have to say that I am much happier with the CNC metal cutting capabilities than my own personal abilities. It was definitely worth $100.00 to me to do it this way. YMMV.

One last thing - the plans show that the holes in the horns are 3/16" diameter. I ended up drilling them out to 1/4" and welding in 1/4" tubing that has a 3/16" inner diameter just as others have done.
Semper Fi,

Terry Hand
Athens GA

gseiter
Posts: 10
Joined: Wed Jan 31, 2018 10:46 am

Re: Waterjetting

Post by gseiter » Tue Oct 30, 2018 9:17 pm

Thanks for all the great information and ideas. Icarusair is down the road from me so will probably use them, especially if they can remove the tabs. I like the idea of the square tubing. If they can't/won't removing them shouldn't be difficult. Thanks again for all the information.


Gene Seiter

Bill Church
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Joined: Fri Feb 24, 2017 8:48 am

Re: Waterjetting

Post by Bill Church » Sun Nov 04, 2018 9:38 pm

Tom,
Bending sheet metal with the grain isn't actually a "NO NO", it just has to be approached differently. When bending with the grain, a larger bend radius must be used than when bending transverse to the grain. However, for optimum strength, and the sharpest possible bend radius, bends should be made transverse to the grain. Speaking of bend radius, I noticed that the drawing TBF9001_AX illustrates a bent part, but the part drawing doesn't show a bend radius. With the grain direction as shown, the part should be bent with a minimum inside bend radius equal to 1.5 times the thickness of the part.

Bill C.

tom kreiner
Posts: 33
Joined: Sat Feb 25, 2017 9:49 am

Re: Waterjetting

Post by tom kreiner » Tue Nov 27, 2018 12:58 pm

Bill, et al,

Sorry it has taken so long to put this together, as I've been on two trips and gone thru a total hip replacement since the last time I was able to post...

In response to your comments regarding the bend radius shown on the prints I uploaded previously, please note that these were hastily added, and were Revision AX, the X implying pre-production. Guess I should have chosen the prints more carefully, but, oh well, at least I get a chance to clarify in this post.

As seen in the A Revision print for the small angle bracket, TBF9001, attached, the radius of the bend is clearly called out. This is carried throughout the entire set of prints I captured in SolidWorks to create the pdf's, and dxf's that I mentioned in a previous post. With over 140 design files in my Piet Metal Fittings folder, I've got a substantial time investment in the package I've put together.

As far as the comment on the bend radius, I'd defer to the USAF, FAA, and historical references shown in the attachments. The first of these is from Sportplane Construction Techniques, Bingelis, p 44, 1998, and the second is from Aircraft Maintenance, Brimm & Boggess, p117, 1940. Both of these pretty clearly suggest the minimum bend radius for 4130 is to be "1T" i.e., one material thickness. That's not to say 1.5T cannot be used, but a larger bend may make it difficult to make a tight assembly as shown in the UCF4001, the Upper Cabane Fitting. Worse, a larger radius may create an eccentric load, or interfere with the bolt head. Increasing the radius should be done on a case-by-case method ensuring that the results derived are the results desired. Note on the Cabane fitting the angled leg has been extended - as Oscar point out - to ease insertion of the bolt.

Hope this helps...
Attachments
TBF9001_A.PDF
(38.84 KiB) Downloaded 32 times
Bend Radius - Bingelis.jpg
Bend Radius - Brimm & Boggess.jpg
UCF4001.JPG
UCF4001-2.JPG

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Richard Roller
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Location: Olathe, Ks.

Re: Waterjetting

Post by Richard Roller » Tue Nov 27, 2018 6:03 pm

This is the info I used when working on certain large aircraft. 8-)
steel bend radius.pdf
(216.89 KiB) Downloaded 65 times

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