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Slitting saw update

I slit the first set of 2″ deep slots for the flat blade, and the angle blade today. Here’s my findings:

  • It is possible to do the entire depth in one cut. However, it did seem to go a bit smoother with the pilot of the 3″ carbide blade.
  • You must enter to full depth very slowly or the blade will stick. I went about 1/3 as fast going in, as slicing across.
  • It worked best at 85 RPM. The equation I found here (along with a few other good tips) would suggest RPM’s of about 43. Our machine could do 36, 54, or 85. At both 36 and 54 RPM’s, the blade didn’t have enough momentum to prevent it from getting stuck easily.
  • Using Mistic Metal Mover, and Boelube really helps to make it cut. I applied both liberally when the blade started to make extra noise.
  • When the blade sticks, sometimes it works to back it off a tad and try again. Sometimes you need to take it out all the way.
  • When something snaps, its almost always the bolt. It pays to take it out even if it seems to tighten up OK. A few times, it snapped, but still held lightly together. Had I continued machining, the bolt would have fully broken off inside the threads and been very time consuming to remove.

Tomorrow, I’m flipping it up and will cut out the flat blade and part of the angle blade.

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Using the slitting saw

I began to use the slitting saw yesterday, and, Boy, is it tough. The issue is that the arbor I bought doesn’t have a keyway, so if the blade catches, it still spins the top half of the arbor, but not the bottom half. This means that the bolt tightens and snaps. I broke 4 bolts yesterday on the arbor. Luckily, we had extra bolts at the shop we could use. If you plan on using an arbor without a keyway, I suggest you head to your local hardware store and pick up 5-10 extra bolts when, not if, you break one.

The solution for not catching the blade would be to go at a more constant rate. However, since our machine doesn’t have an auto-feed, it is really difficult to keep a constant speed. I’m gonna try to rig something up today with a drill, but given the high torque and low speed, this will likely be impossible.

Another issue is, since the blade I bought is High Speed Steel,  I have to be really careful about using it on the material which has been torched, as this could dull the blade really fast. My answer to this was to do one pass with the carbide blade we have on hand to break thru the harder steel. The problem is that this took HOURS. Hours to cut a .5″ deep slit in 18″ of material.

The end of the first slit.

I reccommend doing a test cut in some of the material which will be removed. This way, you can understand the limitations, and if you will need to make shallower cuts.

A test slit to double check the height is correct on the blade. (>1" away from edge)

I’ll likely need to do more than one pass to get the blade to the proper depth. In my trial piece, I found I could only cut about 1″ deep with the 6″ blade without catching the blade.

Fixing the arbor

When the bolt snaps, this could be a difficult repair. As I had 4 snap on me, I had to try a vareity of techniques to fix it.

If you’re lucky, the bolt will snap so that you can simply grab the threaded half with pliers and twist it out. Try this first.

If there’s still some thread sticking out, but you can’t twist it out, you can weld a nut to it, and use a socket to get it out.

If the bolt breaks off inside the threads, the only solution I found is to drill it out. Find out what size drill you would need for that tap and drill with that bit, being really careful not to let the bit get off centered, as this could destroy the threads. I suggest doing this in a lathe if possible.

The worst case scenario, which happened to me, (along with everything else listed) is that somehow, the bolt

The bolt whose head we had to drill out.

doesn’t break, but the threads strip. The bolt will twist, but won’t come out. In this case, you have to drill the bolt out from the head. The problem with this is that the bolt is free to spin, and will start to spin when you drill it. It took a really fine touch (Jimmy’s) to drill it out. He had to come up on it lightly and back off when it started to spin again.

Drilling out a bolt. You can see the threads came off onto the drill bit.

Breaking the bolt is a pain to fix, so be really careful the blade doesn’t stick. If it does, shut the machine off ASAP. Don’t bother with trying to back off the table. Shutting off the machine will be much faster, and safer for your bolt.

Before beginning to build

Here’s a bit I plan on including in the instructionals. Wrote it today. I’ll likely edit it a few times in the coming week.

Bushing Obtainment and Installation

A very important component of the Ironworker is the pin and bushing connections between parts. These parts will be under up to 120 tons of force, so it is crucial that these connections be secure.

The bushings could either be made from 4130 alloy Chromoly Steel and hardened, or purchased from a supplier such as Regal Bushings. It will be much cheaper to make them yourself (cost us $152 for all bushings, would cost ~$ ___ purchased), but does require a few hours of extra work.

To insure longevity of these connections, we suggest the bushings should be either “freeze fit” or “press fit” into holes bored to exact size for them.  This insures the bushings are perfectly centered in the hole, and won’t be able to move or to twist. However, it is likely that boring slightly oversized and welding them in would work.

Boring the hole will require a boring head for a mill, or a boring machine, capable of boring ~3″ diameter holes. The final diameter of the hole will be determined by measuring the outer diameter of your bushings, and subtracting .001″ per 1″ of bushings. The following video offers a good instructional on the boring procedure: http://www.youtube.com/watch?v=VY2crpjhL3E&feature=relmfu

Preparing the “Big Holes”

Boring requires that a hole already exists to be bored to a larger diameter.  For the smaller diameter holes, either mag-drills or drilling would work for making it. However, for the 3″ holes for the big bushings, making these holes will prove to be a bit more difficult.

The easiest way to do them is certainly with a mag-drill. I recommend a 2 3/4″ or 2 7/8″ bit and boring to size. However, it is a very pricey bit ($252 here for a 2 3/4″). For choosing the proper bit, know the following things:

  • The larger the bit, the less boring you will need to do. Boring is very time consuming (takes 4-5 minutes per .03″ removed from a 3″ deep hole) so should be minimized as much as possible.
  • Bits get more expensive with their size.
  • The maximum size bit you should buy is 2 7/8″, as if you purchase a 2″ deep bit, you will need to drill from both sides of the 3″ thick piece to remove all material. I’ve found that despite drilling a pilot hole, the center of the hole can be off by up to 1/16″ overall. So drilling any larger than that risks oversizing your hole.
  • The minimum I’d reccomend is 2.5″, as otherwise, it just takes too long to bore.

If this is out of price range, torching the holes is an option; this is what was done for the OSE prototype. However, torching really hardens the steel and will make it much more difficult and time consuming to machine. (probably 3X longer!)

3/25 Update

Busy few days. Workin hard and playing harder.

In the past couple of days, I made a ton of progress.

I fixed the 2 bushing holes that I messed up, one from a bad freeze-fit, and one from a stupid measurement error. The solution was to weld up the hole and re-bore it. A very time consuming fix. Don’t make that mistake!

I also had to torch away parts of the lower arm to get proper clearance for the cylinder and linkage.

The cylinder space wasn’t accurate because I couldn’t find the spec’s for the cylinders overall diameter, so I assumed it would be 5.5″. Turned out it was 6″. Not a big deal to fix- Just had to torch away the excess. I found where to torch by making an aluminum “mock-up” of the cylinder and using that to guide where to torch.

Torching 3″ is very difficult. Unlike 2″, it requires you to pre-heat the metal from the bottom, or the oxy will have a really hard time making a straight cut. I made the mistake of not pre-heating when I torched the holes in the linkage, and that’s why they came out so badly.

Once I torched away the cylinder space, I could weld the cylinder mount. Should’ve taken video of the process, but it was pretty simple. Basically, I flipped the arm vertically, so the attachment wouldn’t fall, and held it perfectly centered using magnets. After I tacked it, I double checked it’s squareness, and gave a solid 1/4″ fillet all the way around. After that, I ground away any weld material that would block the cylinder. See the photo in the gallery below.

For some reason, the lower arm was interfering with the linkage. I’m still not sure why the linkage space wasn’t right. In the design, I left 1/4″ clearance for it, because I knew there would likely be small measurement errors, and that the lower-arm torching wouldn’t be perfectly accurate. I need to go back and double check all my measurements on the linkage, and the CAD file I sent for torching the lower arm. It could have been as simple as the fact that the torching is only guaranteed by 1/4″ by the metal supplier.

Either way, I torched away the excess, and now it will work.

I also freeze fit the remaining bushings for the hole’s I’ve bored. I will need to do one more batch of freeze fitting when I’ve completed the upper arm. Here’s a vid explaining the pre-heating; you want to get the steel hot enough so it starts changing colors. Didn’t get any shots of putting the bushing in cause my camera ran out of juice.

The final freeze fit got stuck midway thru. I was going to take it to the press to push it in, but the guys volunteered to help me. My little girl muscles weren’t enough to hammer it further in, but Mike’s most certainly were! That’s one heavy hammer.

After the freeze fits, I had to grind down whatever parts of the bushing were sticking out of the material; some of the material was thinner than specified, so the bushings were sticking out. This could cause a problem because when the pins are in, they will need to be clamping down on the entire piece, not just the bushing. If it’s just clamping on the bushing, the metal could end up slipping out further on the bushing, causing the arms to get out of parallel. This would destroy clearance accuracy with the blades, and result in either sloppier cuts, or broken blades.

3/21 update

I was on fire today! I wish it was figurative, for if anything, I was the opposite of “on fire” in terms of my working speed today. But alas, it was literal. Its been a while since that happened. Its kinda exciting every now and then. It burnt the hose too, on the torch.

So, first thing today, I was gonna freeze fit the bushings. I did one yesterday with just normal ice, and it worked fine, I just had to use the press to push the bushing in. I figured I didn’t need to buy dry-ice, since it worked. I was wrong. I did one successfully today, using the press. The second one wouldn’t go all the way thru. I flipped the piece over and discovered horrible galling, and material  displaced! After talking to the guys, I found that was because the bushing must have gone in sideways, and the press kept pushing it in , so it scraped away excess material. They said this happens to the best of em now and then, that they’ve all done it. See vids.


Seems like there’s really not any way to prevent it if you’re using a press to put them in. You can be more careful that it doesn’t get cocked, but it’s really hard to tell when you’re doing it.

My solution is simply to use dry ice. It worked really well before, and it’s relatively cheap (~$6.50 for 5lb). Best part is that it will make the bushings go in with just a hammer. Or even with your hand.

I shipped the welder to OSE today. It took up about 2.5 hours to get it shipped. Jimmy taught me how to use the packing machine. I forget what it’s called, it uses metal straps and crimpers. I also shipped the cylinder and a gas cut-off saw that Marcin bought from my uncle. See the pics in the gallery below.

I began on the cylinder mount. I did things in an odd order because it was so small. See video below. First I torched the radius, but didn’t torch it off. This is so I could have a center mark to torch from. Then I mag-drilled out the mount hole. After that, I torched it into a piece slightly bigger than the mount. This was so I would have something to clamp it to while I machined it down. Then I machined it to the proper thickness, and bored the hole to exact diameter. After that, I finally torched to proper size. See photos.


3/9 update

Yesterday, I finished up the Main Linkage, and drilled the remaining holes in the Lower angle mount.

The finished Main Linkage (OK I still need to sand and freeze fit, but this only takes a few minutes)

I tried to saw off the extra material on the linkage, but ended up breaking 2 blades attempting to saw the material. I’ve determined I’m not strong enough to properly use it. Jimmy ended up cutting off most of it. I broke the last blade in the middle of a cut, so we had to torch off the remainder. (see video below)

Then I milled the rest of the material so it was 1 1/16″, to fit the cylinder. This took ~4 hours. Unfortunately, I didn’t open up the cylinder until I’d already machined it, and the opening between the ears was actually 1 3/16″, different than what the specs said. This pissed me off because I probably spent an extra hour machining off that material, because the specs lied. This taught me a valuable lesson– check materials which have been received for their specs. Don’t assume they match.

I also drilled and bored the hole for the cylinder mount. See the video below about the difficulties I had mag-drilling the material.

Also, I finally ordered the fastener from Bolt Depot.

On an unrelated note, I just sold a $350 bookshelf, so many of my recent money worries are over! Might take a bit of time away from fabrication, but I can afford gas for another month!! I’d been in a bookshelf slump for all of Februrary, and had only sold $55 worth of merchandise. I have enough saved to last a few more months, but lack of income scares the pants off me. Huge weights have been lifted from my shoulders.


3/8 update

I finished putting the holes in the Lower Flat Mount today, as well as drilled the holes for mounting the blade for the angle blades. See the photos and video below.

I’m going to wait to weld the table and angle support on until I have the machine assembled. I may need to machine away some of the mount to make proper clearance for the blades. Waiting insures machining will be much, much easier. Also, its either machining that, or machining the upper arm more, which is very un-desirable.

I broke the blade trying to cut the linkage today. Purchased more, and will try again today. If I’m successful, I’ll machine the rest of the main linkage and be done with it tomorrow.

I’m also ready to start on the lower arm! I’ll start by mag-drilling the holes for the linkage pin holder, and main pin holder.



Transfer punching the holes for mounting the blade