I Didn't Like the Pulleys on My Drill Press

Printable View

Nov 8, 2020, 02:50 PM
Crusty

12 Attachment(s)

I Didn't Like the Pulleys on My Drill Press

So I decided to make new ones, casting them in aluminum and then machining to final form.

So first I needed a furnace to melt aluminum. I made one from a Homeless Depot bucket, some Kaowool and a refractory coating. I needed a propane burner too so I made one from steel pipe and other scrap steel with a hair dryer for a blower. I used the handle valve from a propane torch to control the gas into my furnace and a waste gate on the feed tube controls the air into the burner.

Attachment 37180

So then I needed things for casting. I bought a crucible then I made lifting tongs and a pouring shank for it, as well as a pair of general grabbing tongs, a stir rod and a dross remover, along with a mold for ingots.

Attachment 37181

What else? I need a flask to mold the parts in so I made one.

Attachment 37182

I needed greensand for molding so I sifted and mixed up two tubs of facing and bulk greensand plus made a screen sifter.

Attachment 37183

OK then, I intended to use the lost foam process so I needed a hot wire cutter to make the forms. I made this one using a 16 banjo string which seems about the right resistance for the 12v, 2 amp battery charger.

Attachment 37184

What else? I needed some aluminum to cast so I bought a Kia engine from a junkyard, disassembled it and then broke it down into chunks which would fit into the crucible.

Attachment 37185 Attachment 37191 Attachment 37186

And the spirit sayeth unto me "Goest thou forth and cast thine ingots upon the mold, and so I did for the most part though I slipped on some lion scat and struggled to finish a weak sixth.

Attachment 37187

Those are 5lb ingots and I got 11 of them from that engine. The aluminum seems to cast well.

So finally I was ready to try to make some castings. Here's a couple after rough machining and one straight out of the mold. It took a couple of attempts and the lost foam process left pretty rough surfaces so I'll likely use the traditional greensand casting method in the future, though making foam forms is a time saver over wooden ones.

Attachment 37188

And here are my pulleys with the external machining done.

Attachment 37189

And here they are fitted to my DP finally.

Attachment 37190
Nov 9, 2020, 05:06 AM
DIYer


Thanks Crusty! We've added your Furnace to our Forging and Casting category,
as well as to your builder page: Crusty's Homemade Tools. Your receipt:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/homemade-furnace-9"> <img src="/uploads/237810/homemade-furnace-9.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/homemade-furnace-9">Furnace</a> <span> by <a href="https://www.homemadetools.net/builder/Crusty">Crusty</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/furnace'>furnace</a> </div> </div> </div> </div>
Nov 9, 2020, 05:10 AM
DIYer


Thanks Crusty! We've added your Casting Tools to our Forging and Casting category,
as well as to your builder page: Crusty's Homemade Tools. Your receipt:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/homemade-casting-tools"> <img src="/uploads/237815/homemade-casting-tools.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/homemade-casting-tools">Casting Tools</a> <span> by <a href="https://www.homemadetools.net/builder/Crusty">Crusty</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/tongs'>tongs</a>, <a href='https://www.homemadetools.net/tag/crucible'>crucible</a> </div> </div> </div> </div>
Nov 9, 2020, 05:14 AM
DIYer


Thanks Crusty! We've added your Drill Press Pulleys to our Drilling and Drill Presses category,
as well as to your builder page: Crusty's Homemade Tools. Your receipt:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/homemade-drill-press-pulleys"> <img src="/uploads/237820/homemade-drill-press-pulleys.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/homemade-drill-press-pulleys">Drill Press Pulleys</a> <span> by <a href="https://www.homemadetools.net/builder/Crusty">Crusty</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/pulley'>pulley</a>, <a href='https://www.homemadetools.net/tag/drill-press'>drill press</a> </div> </div> </div> </div>
Nov 9, 2020, 07:22 PM
trigger

You do know Mc Master delivers ,saves you slipping in the Lion scat especially if it might still be lurking in the yard somewhere.I also recommend Chevy or Ford to keep it Made in the USA...;-)
Nov 9, 2020, 08:49 PM
metric_taper

The last time I priced step V-belt pulleys, there was shock. So what was wrong with the original ones on the drill press?
Nov 10, 2020, 06:16 AM
Crusty

Fantastic plastic slippers and replacement belts were unavailable so I converted to higher torque standard 3VX series belts on the new pulleys.
Nov 10, 2020, 06:58 AM
metric_taper

Quote:

Originally Posted by Crusty

Fantastic plastic slippers and replacement belts were unavailable so I converted to higher torque standard 3VX series belts on the new pulleys.

I compliment you on all the tools built to do a casting, the cope and drag, the hot wire cutter. Did you make a crucible from steel pipe?
I see you put the aluminum block on charcoal, was this to burn the oil film off? I didn't see how you would catch the melt into the ingot form you showed.
Was the foam that white styrofoam 3/4" sheets you get from the material supply?
That took some doing to hog out the V-grooves with a form tool. Takes lots of time as I know you can't grab the casting in a way that just lets the machine whittle away the unwanted. I don't see the chatter in any of the surface finish in the grooves.
Sorry for so many questions....
Nov 10, 2020, 07:53 AM
Crusty

The shocking prices for step pulleys is the primary factor which drove this project.

I bought a clay graphite crucible since I intend to make more castings and steel crucibles don't last very long. The PMC brand seems to be OK. Buy your crucible first and then build the furnace around that crucible so that it all fits when you're done. Two inches of Kaowool is plenty. Closer walls to the crucible improves the heating of the furnace but there has to be room enough to get the lifting tongs in there.

I highly recommend that you build a forced air burner rather than a naturally aspirated one because it can be tough to get a natural one sized to draw correctly. A hair dryer with a blower setting provides more than enough air and you can discharge the excess air through a waste gate, plus the propane orifice isn't a critical dimension on a forced air burner.

I was trying to anneal the aluminum block so that I could bust it up with a sledge. It didn't get hot enough and only worked for the lowest section but I thought the pic was cool. The fire no doubt helped but I still got a lot of dross when I cast the engine into ingots, but $40 for 55 lbs of ready to cast aluminum is still a good deal to me.

The form is just a tray made from a piece of angle iron with ends welded on and I pour the ingots from the crucible. The open corner points upwards and it produces long triangular ingots which can be readily cut into crucible sized pieces on the bandsaw.

I used the extruded insulating foam from Homeless Depot rather than typical expanded polystyrene foam. Half inch thick and spray adhesive to join the pieces.

I plunged with a cutoff tool into the middle of each groove to the proper depth and then cut tapers on either side using the cutoff tool again and the compound set to the correct half angle for each side. Didn't take long and left nice surfaces. The central plunge provides relief so the taper cuts go easily and quick. Form tools can be a pain to use on a small lathe. Touch up the tool cutting edge often because it deforms in the process.

I'm going to make two of the three pulleys over again because with my limited fixturing they didn't turn out concentric enough for me (I want my DP quiet and smooth). I've ordered a couple of mandrels with expanding collets to turn the new pulleys on between centers so I can guarantee concentricity. Doing it like that I'll be able to machine all important surfaces without changing my fixturing so that the part stays centered.

If you don't have to turn the part around then mounting a central hole drilled through the rough part onto a bolt chucked up with the head behind the jaws and a nut forcing the part into the chuck can work, but the bolt ought to have a divot on the end for the live center in the tailstock so that it's exactly on center and the central hole should be a close fit to the bolt shank (mine wasn't close enough).

It's worthwhile to make all this stuff because it's a joy to unmold a pour and see a rough casting which can be made into something useful, and melting metal is flat out fun. Buy a pair of aluminized leggings and wear good boots which you can get off quickly just in case.
Nov 11, 2020, 05:57 PM
Saltfever

Very nice. I can't see from the finish-machined pics; how was the porosity? You mentioned skimming dross/slag but did you do any out gassing before the pour? If so what did you use?
Nov 11, 2020, 06:14 PM
Crusty

There was some but it was widely separated small dots and to me didn't affect the integrity enough to be concerned about.

I first intended to use Light Salt to degas the AL but several videos I've watched since have convinced me that it doesn't work so I just poured the metal trying to keep impurities to a minimum. Apparently you need a costly bubbler rig to achieve significant degassing. I did use a smallish tapered sprue along with the Campbell pouring basin design which eliminates gulps of air while filling and there weren't any voids that I saw during machining. The foam outgassing as it vaporized left a terrible surface though.

That just reminded me that I forgot to take a picture of and mention that I made a fixture to turn wooden tapered sprue forms on my table saw.

Another metal casting tip that I forgot to mention: Plan all your moves in advance so that you can setup for the pour and make it with no improvising or adapting during.
Nov 12, 2020, 03:16 AM
nounours2

bravo beau travail
Nov 16, 2020, 02:52 AM
Saltfever

Quote:

Originally Posted by Crusty

. . . . Apparently you need a costly bubbler rig to achieve significant degassing. I did use a smallish tapered sprue along with the Campbell pouring basin design which eliminates gulps of air while filling and there weren't any voids that I saw during machining.

Years ago I remember using some cheap tablets to degas. Can't remember the chemical but I think chlorine was part of the mix. Supposedly, it combined with the hydrogen gas in the aluminum to out-gas hydrochloride or sumptin equally as toxic. The "bubbler" was just a simple, small, steel cup with holes I drilled in it and welded to the end of a steel rod. Drop the tablet on top of the molten aluminum and then plunge the cup and tablet to the bottom of the crucible holding it there while it dissolved creating a lot of gas that would bubble up to the top carrying impurities with it.
Nov 16, 2020, 07:49 AM
Crusty

Light salt is a mixture of sodium chloride and potassium chloride and the combination of the two breaks down under heat to release chlorine which entrains hydrogen as it evolves from the melt. From the videos I've watched testing the premise it doesn't work, however none of the testers melted the salt into a hard cake before plunging into the melt, a step reported to be essential.

In any event, the presence of impurities and voids is more a function of feeding and venting system design than of formation of undesirable hydrogen in the melt and care in making these two factors perform optimally is rewarded by good castings. The inclusions are most often aluminum oxides which have formed during the pour and are not driven out rather than being due to hydrogen entrained in the pour.

My dross skimmer is a flat plate which has also been domed to push a slug of light salt down into the melt but I didn't do that in my pours. Possibly I'll try it with a hard cake in the future but for now I'm concentrating on getting my fill velocity right along with correct filling and venting.
Nov 16, 2020, 08:58 AM
rebuilder1954

Well done, Crusty!
Nov 17, 2020, 10:53 AM
Crusty

1 Attachment(s)

Just poured a replacement pulley using the traditional greensand method with the previously mentioned features to improve the pour and I believe this is my best pour yet. No voids or inclusions that I've seen, no shrinkage defects and there's good metal underneath the dingle berries. The surfaces are much better than the lost foam attempts too.

Attachment 37269
Nov 17, 2020, 03:38 PM
metric_taper

I remember back to metal shop class in 1973, we poured aluminum. I somehow recall the teacher using mothballs to degas. But I can't find any reference to that on the internet, only that it's naphthalene, C10H8. So a hydrocarbon. Found youtube video of guy using backing soda, that comments refute as BS. That indicates salts of Fluoride or Chloride are used. I did see a site where this can be purchased.

Looks like you really don't need that.
Your earlier post, you said you used a parting tool to cut the V groove faces. Did you have to do some grinding to give clearance for the blade in that angled slot? Trepanning operations are always a pain.
Nov 17, 2020, 04:47 PM
Crusty

The part was turned while being revolved on it's bore so it was just plunge cuts from the side. I tried the mandrel with expanding collet turning between centers and I was able to rework the pulleys with straight bores easily to minimal runout.

As I said, light salt - a mixture of sodium chloride and potassium chloride, which liberate chlorine and that in turn entrains hydrogen. Many internet metal casting fan boys are about to have a stroke over degassing when the problems are primarily due to aluminum oxides formed and entrained into the melt by poor metal delivery systems. It's likely that your teacher used a degassing pellet which looked like a mothball.
Nov 18, 2020, 02:55 PM
Crusty

1 Attachment(s)

I got the replacement pulley that I cast yesterday rough machined today. I made the largest pulley a little bigger than before to get my lowest rpms even lower and I left the unimportant surfaces as cast rather than taking meat off to pretty them up and weaken the part.

I wish I had tried mandrels and expanding collets long ago because they're working great to turn these parts with features that need to remain concentric to the bore. I've known about them for a long time and just never got around to trying them and now that I have I see the potential for improved machining.

Attachment 37279