Tubing Bender

This is what the finished tubing bender will look like.  The Plans were purchased from Solution Design

Here's a picture of what will be the frame for my hydraulic tubing bender. I decided to cap off the ends of the tubing to give it a more finished look and to also make it a bit safer, having the tubing capped off like that and ground smooth makes it less likely that you'll cut yourself working with it and moving it around.

The following pictures are of my progress as of Saturday March 11th 2006

Here it is with a fresh coat of paint. Unfortunately the paint was old and the temperature was a bit cool so it came out pretty flat, but I'll probably end up adding another coat to it at some point.

Now I've got to get busy working on the bending die and follow block. Stay tuned for that part of the project.

Here are some pictures of what I did this evening. I basically decided to try doing the die as a lost foam casting, so I needed a way to create the shape I wanted. I settled on making a special arbor for this old electric motor I've had floating around for years. Basicall it's an arbor that I can make different parts for but as is it has a 1" piece that goes through the 2" thick foam, and there are flanges on both sides. This way I can turn any number of diameter dies without having to do it on my metal lathe. I hate getting foam on my metal lathe.

here's a picture of the motor with the arbor I made. The 4x4 was just there as a rest for the lathe tool, to make it steadier.

Here's the foam pattern for the bending die. After it's turned to shape it will be cut to the proper 120 degree shape on the bandsaw.

To get the radius in the foam I first made a plunge cut with the lathe tool to a depth almost as deep as half the tube, then I wrapped some sandpaper around the tube and gently lowered it into the groove, this rounded out the groove and made a nice fit around the tubing.

Here's another shot showing the tube in the groove, I was testing the fit of it. This is the same tube I wrapped the sandpaper around.

Here you can see it on the 1" shaft on the bender. The fit turned out really well.

Stay tuned more to come........

And here's some pictures of the foam bending die casting pattern.

This is made from the pink insulation foam that you get at the hardware store. I've used hot glue to glue on the sprues and riser. I'm going to try doing this lost foam casting in my petrobond instead of just lose sand, I think it might work better.

You can see how the foam has the radius for the tube already in there. If I can't cast it that way I'll probably just consider buying them, although I would really hate to have to do that, it would be really nice to be able to cast these myself from the scrap aluminum that I have, and it would be a heck of a lot cheaper. Well I'm sitting here debating on whether or not to go ahead and try and cast this today.

Casting the Die

Well here are some pictures of the casting process that I did today to cast the die for my tubing bender. This is a 3 1/2" radius die for 1 1/4" tubing. I'm using schedule 40 for my project since it's readily available, cheap, and the wall thickness is slightly thicker than the DOM tubing called for in the plans. I'm sure it will be more than adequate for the project. So without further delay on to the pictures.....

here's the foundry setup right after I poured the lost foam mold. I decided to use my petrobond casting sand this time instead of loose sand. I'm glad I decided to vent the heck out of it to, it really needed all those vents.

You can see little strings of aluminum that pushed up out of the vent holes, I have to say that they really did their job. It's hard to make it out but in the pressure head tool ( the pipe with handles ) you can see where the aluminum in the middle has sunken down a bit, this is why this tool is critical in lost foam castings, keeping that pressure at the entry to the mold allows it to keep pressure and keeps a supply of metal there, so as the mold fills and the metal shrinks it keeps it from having voids in it.

Here you can see the steam escaping from the vent holes.

Another shot of my foundry setup

Here I'm cleaning out the sand around the part and man does this stuff smoke. hahahaha, I had to turn the fan on to keep from being choked out.

And here it is straight from the casting sand. you can see where the vents were and you can see that I accidentally pushed them all the way through the pattern. it doesn't really matter, it just would have looked better if I hadn't. Also I'm going to need to take the dremel tool and clean up some spots in the radius where the vents left little bumps.

Another shot of the part showing the hole through the center. Unfortunately I'm going to have to run somethign through this hole to clean it up a bit since it didn't come out a perfect circle. I almost turned down a steel liner to go in there so it would have a nice smooth finished bore, but I guess my impatience got the better of me.

And here it is with the sprues and riser cut off and some of the bumps from the vents cleaned off. I'm sure it will look a bit better when I get all the bumps cleaned off and get the part cleaned up as a whole. Well that's it for now. The next part will be making the follow block, which after todays success I think I'll do the same way using the lost foam method. Until then..........

I decided to mill the bending die a bit on my drillpress that I converted into a mill, I thought it might dress it up a bit, it really has no bearing on the usability of the part I just figured it would make it look nicer and it would give me a chance to see what difference using the degassing additive made. I can say that it made a huge difference.

I'm really happy with the way it turned out. Unfortunately the radius doesn't match the tubing perfectly so I need to make some kind of cutter or sanding drum to clean up and finish out the radius. But it's pretty close as is.

Well today is Saturday the 25th of March and this is what I got done on the bender project today. I made the foam pattern and cast the follow block for the bender. I decided not to show the foam pattern or the casting since it would just be redundant. The process for making this part is the same as it was for the bending die except that this part was just cut out on the bandsaw rather than turning it on the arbor. One thing I did different on this part was that I hot glued the foam pattern to the piece of tubing so when I cast it the tubing itself would create the radius, worked really well and the finish in the radius was really nice. This part seemed to have more surface defects on it than the bending die did, I don't know if was because there was more metal in this part or if it would have been better to just do it in loose sand instead of the petrobond. Luckily the defects seem to only be on the surface and not into the part, and again the degassing additive and flux have really seemed to make a difference, I haven't noticed any porosity problems on this part.  This part didn't turn out as pretty as the other one but I don't really care, as long as it's structually sound and the radius matches the tubing it really doesn't matter what it looks like. The two short sections sticking down from the bottom will slide into the 2x2 tubing that will be welded to the 1/4" strap that bolts to the short piece in the middle of the frame.


I borrowed a belt sander from my Uncle today and I have to say that I think that's my preferred method now for cleaning up castings. hahaha So much quicker than using my little drill press to mill it down.

The follow block has had more surface defects than the bending die, fortunately I don't think that any of them are going to cause any structural problems, they seem to only be on the surface or a few thousandths deep. The belt sander did a really good job of cleaning up the castings so I guess that's a good enough reason for me to start building a belt sander before to long.

This part didn't come out nearly as pretty but I don't really care about how it looks. I think that because of the shear volume of metal there was just a lot of foam in that pattern, and I think that just creates to much gas, it might have been better to cast that in loose sand rather than the petrobond but I was affraid to try it because I've had mixed results in the past doing that and I didn't want to have to redo the casting. After I finish the project I'll probably try casting some of the parts that way and do it in the loose sand to test it out and see what kind of results I can get. I've got enough scrap metal that I could probably cast some of these to sell, of course that would only be after I cast all of them I might want for different diameters of tubing and different radius.

I'm also going to change my plans here a bit. I had originaly planned to have the to short pieces on the bottom slide down into the two vertical pieces of tubing, but on second thought I'm going to do it different. I'm going to have a 1/4" plate welded at the top of the two tubes and then just bolt the follow block to that 1/4" piece of steel. It will be simpler and easier to get the bottom parrallel with the top of the follow block.

Milling the Follow Block

Well I'm happy to say that I've finished both the bending die and the follow block. I got the follow block milled down tonight on the drill press so that the radius for the tubing and the bottom surface would be parrallel. The following pictures are screen grabs, you can download a video of the process.
Right click and save as  The Video

This is how I adjust the depth of my spindle. The dial has 50 marks on it and I'm using a 1/4-20 threaded rod fixed to the spindle. Each mark represents 1/1000th of an inch.

You have to take pretty light cuts with this setup, but other than that it works great. I usually take about .010" cut per pass.

The handle on the left is a locking handle I machined to replace the return spring on the spindle. I loosen this, turn the dial to the desired depth, turn the handle to lower the spindle unitl the dial makes contact with the machined surface of the pulley, then tighten the handle to lock it in place.

I put the tube in the raidus so I could use that as a reference to machine the bottom parrallel with the tube.

Here I'm starting on the other half of the bottom.

Here's a good close-up showing my progress on this side of the follow block.

This was the last pass and I'm cleaning up the surface with a brush. I've learned the hard way that freshly milled surfaces can have sharp edges.

And here's the finished bottom surface.

I decided to clean up the top of the part as well to make sure that the tube had the same amount of support on the sides, so I milled them down until they were all even.

Milling the top surfaces.

Test fitting the tubing in the radius.

The finished follow block. Now I just need to make the stand for it to get it to the right height.

I'm almost finished! I just need to finish up this stand for the follow block and then make the l-angle pieces for the bottom of the jack. I got the stand for the follow block welded  up tonight, and despite making a mistake I think it will work out just fine.

My plan was to put a 1/4" plate on the top and the bottom of the 2x2 vertical pieces. Well when I did that I must not have been thinking because when I got the thing welded up I realized I didn't leave myself any place to bolt the follow block onto it. hahahah So since I still had a bit to much gap between the two parts I was able to fit an 1/8" piece between the top plate and the follow block, I then clamped a piece to each side and then welded them together along the seam to form a u channel. the 1/8" channel will bolt to the follow block and then there will be two pins, one in each tube that passes through the 1/8" plate, through the tubes and out the other side. So it worked out ok in the end.


A Major Setback

Well I finally had the bender all finished up today and decided to try making my first bend with it and SNAP!!!  As I figured the casting for the bending die wasn't strong enough around the 1" shaft that holds it in place. I can't say that I'm the least bit surprised by this, something kept telling me as I was working on this that it was going to happen.

As always porosity seems to be the main culpret here. I'm not sure why I had such bad porosity in this area of all places. I even used commercial degassing tablets in this melt to reduce this kind of thing.

Here's the other part. As you can see there is a major void in the metal and the porosity is pretty bad.

The bending force also bent the 1/2" shaft that holds the jack to the frame at the top. I think this could have been avoided a bit if I had made spacers to go on each side of the jack shaft. I have a bit of space in there and I think that was the main problem for this part. The bolt on the bottom is what went through the 1/4" angle into the die and tied those together. Surprisingly the bending die didn't seem to have any problem at either place where the strap goes around the pipe or where the jack hooks to the die.

Here you can see some of the parts I made this weekend. I finished up the stand for the follow block today. There are two parts there that are red, the channel gets bolted to the bottom of the follow block and then that has two bolts that go through it and the two vertical tubes on the stand. You can also see the strap that goes around the tubing and the two 1/4" L-angle pieces that bolt to the bottom of the jack.

Here's another shot of the stand for the follow block and then the follow block in the back.

Well I guess that means it's back to the drawing board to figure out how to make these dies and make them strong enough to handle the stresses of bending the 1" schedule 40 tubing.

Well here's the new bending die design that I'm working on

I wanted to post a couple pictures showing the finished stand for the follow block.

The Kohler Engine

You know I don't know why it took me so long to get around to taking some pictures of the old 23hp Kohler engine that my boss gave me. But I did take some tonight and I thought I'd throw them in here as well.

yep, it's dirty as can be, but you can't beat the price. hahahaha

I believe this is an old K582, and from what I've been told by the guy at Kohler it's a cast iron engine, so I'm going to have to lose some bits here and there to lighten it up a bit.

Here's a shot of the back. This particular engine was used on a carpet cleaning rig, so that's why there are some extra hoses in there that I won't need.

It's pretty grungy, but I bet with some TLC and a bit of bead blasting it will turn into a pretty nice engine.

Eureka!

I think I've finally come up with a simple solution that pretty much anyone with a drill, and die grinder could make, and it's steel so it would be extremely strong.  Ok here's the basic idea......

If you make the total die thickness an even amount, say 2" which is what my cast die was then you could take 1/8" steel plate and cut 16 individual cross sections of the die. Then where the holes are you can rosette weld the plates together. Plates could be cut different sizes based on their position in the die itself, which would leave a rough trough where the radius for the tubing is. Then by using a 1 1/4" sanding drum on a die grinder you could finish off the radius for the tubing. The plates could even be bolted together if you don't have a welder to weld them together. ... .It's a simple solution to a $135 problem.  For cutting the steel I usually use my circular saw with a cutoff wheel in it, and it makes rather quick work of 1/8" steel, a hole saw could cut the 1" diameter hole in the center (that's how I did the holes in my bender frame) and well a sanding drum isn't that expensive. Last time I was over at the scrap yard that had a couple of huge stacks of 1/4" steel plate, and at $0.20 per pound the die would  be pretty cheap.  Sure you'd have to put in some time making it, but if you didn't have $135 for a commercial die then it could be a viable solution to the problem.

Final Die Design

I've been working on this die design tonight. I think I've come up with my final design. This is a 3 1/2" radius for a 1 1/4" tube. The die is 2" thick and consists of two 1/4" plates and twelve 1/8" plates. The die as is is designed to be screwed together eliminating the need for a welder to make it. The left side of the die is countersunk and the opposite 1/4" side is threaded for the eight 1/4-20 screws.



I'm going to try and get by the steel supplier tomorrow after work and pick up the the 1/4" plate and 1/8" plate so I can try and work on this over the weekend. I really want to get my bender project finished up and this is the last step.

Here's a picture of what the patterns would be. Material would be one 6"x12" piece of 1/4" and one 12"x36" piece of 1/8" material




Steel Bending Die

Well I've finally made some progress on the steel bending die. It was kind of a pain since I didn't have a bandsaw to cut them out on but if I did, I'd do it again in a heartbeat. My total investment in the steel bending die is about  $27 total, which isn't bad when you consider that the commercial die is a $180. Here are some pictures. I didn't spend much time trying to make it all pretty but hopefully this one will be strong enough to bend the 1 1/4" steel tubing.

You can see here how the different size plates create a radius , albeit a jagged one, but the idea being that by making the different size plates you can finish up the radius with a drum sander.

Well that's all for now. My next step will be to clean up the inside radius and drill the 1/2" hole in the front section for the strap to bolt to. I have a 1" sanding drum but wouldn't you know it, it's bigger than the diameter of the tubing, so I'm going to have to get a smaller one. Otherwise I'm affraid that when I sand and smooth the radius on the inside it will be to large and not fit the tubing right.

Well if you haven’t noticed by now this project is on the backburner so I moved it to the past projects section. The only thing left is to drill a couple of holes and trim off some metal from one of the angle pieces, which you would think would be a short process but everything seems to have taken a backseat to getting the house fixed up. So for the time being this is on hold and now considered a past project. I’ll update it as soon as I can with the results of the homemade bending die.

Later......

HOME