Compressor Refurbishment – Part 5

Time to clean everything up. I pulled the rusty valves apart (after cleaning the outsides up), and they range from not rusty at all to very, very rusty inside.

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The inside and top sealing surface of the crankcase cleaned up. See that tub next to it? That sludge was inside before. Yuck. I’ve already cleaned off most or all of the old gasket at this point.

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Here’s what the old gaskets looked like (I mostly removed them with a razor blade and a plastic scrubber).

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Installing the new gasket at the other end.

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And all back together.

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After flipping it on, there seems to be some knocking in the valves and the hydraulic pressure is low. So a little more work to get over the finish line.

Shars 440V 4″ Vise Review – Part 2

Got the Haimer in the spindle and off we go. Note that nothing here is statistically significant and the equipment being used is really not the right stuff (a Faro arm, or at least a large surface plate and a good indicator, would be a better choice but aren’t available), so take the results as you will. This is good enough for the work this machine does, and to confirm I’ve spent my money less poorly than I would otherwise.

Jaw alignment: measured at 0.0005″ off over 4″. I got the fixed jaw flat, zeroed out the indicator on the left side of the moving jaw, and got the reading shown below on the right side.IMG_3098.JPG

Parallelism (to spindle): 0.0006″ over ~5″. The bed drops away on the side further from the spindle. I will admit that it’s just as likely this is the machine. I didn’t have a piece of ground stock to test it lying around.

Clamping displacement: 0.000″. Unclamped and clamped shown below.

I’m happy with it so far, time to drop in some soft jaws and make some parts.

Compressor Refurbishment – Part 4

Mounting the crankshaft on my little lathe turned out to be pretty straight forward: using my Noga indicator holder again, this time with the cheap Fowler indicator from my last post followed by a 0.0005″ B&S indicator, I got the rear main journal bearing  centered in the chuck. I then followed the same procedure to get the front main journal bearing centered in the steady rest.

The plastic sheeting is to keep the carbon in the cast iron from getting on the ways. In retrospect I should have use something hard, at least between the chuck and the follow rest, to make cleanup a bit easier. Still, no harm no foul.

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I’ve done long work a few times on this lathe (primarily drilling out aluminum paintball barrels for sizing inserts), and knew I’d need to add a modification to turn cast iron (because of the force involved). The original steady rest jaws are bronze with no rolling components. I added some small bearings with simple shoulder bolts into the jaws. Not my favorite solution, but very easy. I think it’s likely I’ll go back and make a set of jaws that supports the bearings on both side in the future.

The original shaft was 01.375″, I took it down to 1.290″.

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You can kinda see this in the above photo, but this makes it very obvious that the old center (which I used to mount the gear puller when I removed the pulley) is no longer centered on the new shaft. This should not be a problem.

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Similarly, the keyway is no longer parallel to the shaft. This could be recut on the mill, leaving a little unused slot on each end, but I decided to accept a shorter key in this case.

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I forgot to take pictures while making the spacer (made from 1.185″ ID, 1.375″ OD 4130 tube) and test fitting everything, so we’ll skip to putting the bearings on. I initially tried to hand fit them by putting them in the oven, but I guess the clearance wasn’t quite enough at 250°F, so I pushed them the rest of the way on. They slide around two tons of applied force.

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To be followed by some cleanup on the rest of the unit, then reassembly!

 

Shars 440V 4″ Vise Review – Part 1

I’ve gotten tired of the cheap vises I originally bought with my machine (both low quality Chinese or Taiwanese units), as well as the used double station vise I picked up off Ebay (which I don’t see a brand name on). I set out to find some new ones with a few goals:

  • Maximize density on the table.
  • Get ‘good enough’ accuracy. Most of the time I don’t expect my machine to hold 0.001″, and never better than that.
  • Minimize cost.

I started by looking at vises in general, but primarily 6″ and 4″ units. After screwing around in Solidworks a bit, I confirmed that there is really no way for me to fit more than two 6″ vises from any brand on my table without significantly reducing Y-axis movement. That’s probably fine for most of what I do, but I have some small parts I’d really like to be able to drop a lot of in these, so higher density would be nice.

Once I focused on 4″ units, it really came down to a few options:

  • Glacern
  • Shars
  • Quad-I

Quad-I is unfortunately out of business, but based on my findings on Practical Machinist and Ebay they made some stuff that would have been perfect. Probably would have been too good (and pricey) for use in the case, but regardless not an option.

Between the Shars and Glacern vises there were a few things to compare:

  1. Glacern offers matching bed heights, Shars does not. I don’t think this will be critical for me, but something to keep in mind.
  2. Price: Glacern $360; Shars $250 (plus shipping for both).
  3. Overall length: Glacern lists theirs as 13.2″ long, versus Shars at 13.779″ (I’m thinking they shouldn’t have listed that level of accuracy though…).
  4. Distance between jaws: both give dimensions with 0.59″ thick jaws, Glacern says 4.05″, Shars says 6.02″.
  5. Similar overall width: Glacern at 6.35″, Shars at 6.535″.

Both units take standard jaws (3/8″-16 bolts on 2.5″ centers); standard mounting dimensions (5.25″ centers); 2.25″ +/-0.0005″ bed heights; use the wedge & hemisphere type anti-lift jaw (Kurt invented this as ‘AngLock’); have integral key and double bolt fixed jaws.

If I were putting this on a Haas or Fadal or other serious machine I would likely never have looked at Shars at all, but I figured in this case it was worth it and bought two. I can fit three (and squeeze in half a fourth if necessary), but this should be good for now.

Unboxing time. Pretty clear that they’re reusing boxes from other parts for the external shipping box. That said, the box for the vise itself (bottom right corner here) at least looks neat.

Inside, there’s two pieces of foam and a smaller box with the handle in it. I’m not actually going to use this handle, but I did notice that it’s just bouncing around in its box (banging on the side of the vice), which seems like an oversight to me. It’s clearly beaten up the box it’s in really well.

The vises also include individual data sheets, although I have my doubts about their veracity (the classic cheap tool QC ‘measurement’ that looks hand written but is printed on is definitely a warning sign here). The numbers in the upper right hands corners do at least match the serial numbers shipped to me.

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The vise itself is in a blue plastic bag with a decent but not overly thick coating of a pretty sticky oil (does not appear to be as viscous as Cosmoline or any of the other really thick oils I’ve seen on other cheap vises).

Once these were on the bed I tried out loosening and tightening them, and these things are seriously tight. No problem with my standard short ratchet wrench that I use on the mill anyway, but still concerning. Upon further inspection, it looks like there is junk in the threads. If that’s gotten into the nut portion of the moving jaw, it may be binding. Alternatively it might just be a very tight

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Overall, the fit and finish is basically what I expected. From a mechanical perspective, the fixed jaw key doesn’t look great. The key itself doesn’t look the same from one unit to the next, and I can’t tell if there’s a weird relief being cut where the key meets the jaw, or if that’s just a poorly ground surface. There are also paints flecks in a few spots that should be bare and bare metal in a few spots there should be paint. I see minimal tool marks on most of the surfaces seen from the top, I’m not sure if these have been polished post-grinding or if this is just a finer ground finish than I’m used to seeing.

The bottom has similar issues to the top in terms of paint. Not a big deal, but also not that hard to get right. The vise includes two 1/2″ x 3/4″ keys but I have 9/16″ slots so they’re not useful to me. It is nice that it has key locations along both axes. The grinding on this side is definitely visible and looks a little non-uniform, I can’t figure out if this is scratches from some other part of manufacturing and not all grinding marks.

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That’s it for unboxing, next step will be measuring these things to see if they match the specified flatness and parallelism.

Compressor Refurbishment – Part 3

Since the compressor is apart, I might as well check out the head and see what needs to be repaired in it. Since the head was off the unit, I pulled out the pistons. Dirty, but overall they don’t look worn or damage, which is nice. The big one is the low pressure piston (compresses air from outside), the small one is the high pressure piston (compresses air from the LP piston).

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Dirt on both will be removed with some disk brake cleaner (it was handy), and they should be ready to go back in. Time to check the cylinder bores. First the low pressure, then the higher pressure.

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Looks like the exhaust valve on this is pretty rusty. Maybe caused by condensation as the hot compressed air is forced out past it? You can see another of the seals here. They’re used at all the connection points, I’ll have to grab a plastic scraper to remove them.

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Not the greatest picture, but again the exhaust valve looks a little rusty. Of course, to pull the valves I had to drop the head back on the crankcase. Poor planning on my part.

Those are some pretty rusty valves…time to clean those up, order replacement gaskets, and pull the bearings on the crankshaft so it can be mounted onto the lathe.

Mill Upgrades – Spindle Motor – Part 1

The first order of business is to uninstall the old motor. That’s pretty simple: unscrew the wires in the junction box, pull the four bolts that hold it to the head, and lift it off. At 50 pounds, it’s heavy but not too difficult (note I’m 6’2″ and 230# — possible bias).

While I’ve got the chance, I’m going to pull the gears from the stock drivetrain out of the head. This will remove a little weight (any more weight I can remove is a good thing — the new motor is 100 pounds), but most importantly it will prevent the gears from engaging by accident. It’s also a good opportunity to drain the oil from the head.

Gears and gearbox cover pulled off the mill. The shaft closest to the top is the motor driveshaft, the second on is an intermediary that transfers power to the high/low gear shaft, which is the one laying down. The final shaft is more of a collar that fits onto the spindle.

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Here’s the inside of that shaft. It looks like this part was made by pressing a few separately made parts together, although I’m not 100% sure on that. It’s certainly a complex part, with the internally broached keyways for the spindle spline and two sets of gear teeth.

This could probably be removed at this point, but I left it in since it liked helps to stabilize the spindle. This will be particularly important once the belt drive setup is applying force all the way at the top end of the spindle.

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Here’s the top of the spindle. That cover (covered in oil, with the three screws, around the spindle) is the oil seal, which I’ve left in for now.. I’ve drained most of the oil out at this point (into the pan below the head, somewhat visible).IMG_2493.JPG

 

 

Mill Upgrades Roadmap

I figured I’d update this with some of my CAD drawings since I’m still finishing up my spindle motor upgrade. This is kind of a road map of what I want to add to my machine, in addition to being actual CAD parts/drawings that I’ve completed (just waiting on fabrication, testing and improvement). I do most of my work in Solidworks and the rest in Fusion 360, which is also what I use for all my CAM.

1. Upgraded spindle motor with belt drive.
2. Hydraulic power drawbar.
3. 18-tool automatic tool changer (which I’ll talk about in another post in the future).
4. 36″ x 12″ steel fixture plate.

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Most of my CAD parts I try to keep pretty basic. For purchased parts where the vendor doesn’t have a CAD model, I generally I just model mounting dimensions and the outline of the part. For example, the Baldor motor in the picture above is basically just a truncated cylinder and feet. I didn’t worry about modeling cooling vanes, the fan, etc.

For parts that I have to make, I’ll flesh them out complete and usually generate a drawing to work from in the shop.

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The spindle upgrade is pretty simple in theory. It’s just a base to support the new motor and two pulleys, as well as a 10 rib J-belt.

In reality, those pulleys are fairly hard to make. The spindle pulley has to match the spindle splines, which are not a standard broach size. The motor pulley is large, so it was difficult to turn on my tiny lathe (mostly due to limited horsepower), but otherwise fairly straightforward as it just had to fit onto a 1.125″ shaft with a 1/4″ keyway.

In addition, I had originally designed this so that motor position can be shifted using a pair of screws, so the sides are actually rails. This makes installation much, much harder. I have already designed a potential replacement that would not use rails, but I’m hoping I can get this installed by switching out the bolts and being creative with my assembly steps. We’ll see. I’ll do in an in-depth post on it once I’ve gotten further along.

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This hydraulic power drawbar is very simple. It only requires three parts to be fabricated (although the four tubes do need to be quickly faced and turned to length on a lathe as well). Those three parts are very simple: a plate with six holes and a channel, and a plate with five holes (the center hole does require a single point threading operation, but still not very difficult). It’s also pretty cheap — not shown is the most expensive part, which is the hydraulic intensifier. It uses compressed air to pressurize the hydraulic fluid, and allows for a much more compact assembly with higher output force than even a multi-stage air cylinder would provide. I have everything for this ready to go except the spacer used to hold the Bellevilles in place, which I will get to after I’ve completed the motor upgrade.

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Skipping over talking about the ATC for now, I’d also like to add a fixture plate. I generally use a dual position vise at the moment, but long term my projects will mostly be fixtured, and the convenience that a fixture plate gives in terms of change-overs is great. I’m hoping this will be a quick and fun project sometime this spring.