Cheap DIY Wheel Lathe - Community Design Project

[ckpcw]

OK!
[designgasm]

I dig the lathe design - real simple, just what we need. I really like the bearing+seized bearing design - achieves good alignment and minimizes the lathe's spinning components. genius. Standardization via internet components is a good move too.

The more I mess with my handheld-drill attachment design, the more I want to build a more lathe-like machine with a stable motor... flatspotted wheels are WOBBLY! I might try to build something like your design tonight while I'm waiting for the Leonid meteor shower (first peak tonight 0900 UT = 1am PST)

EDIT - I like your tool design too - using "passes" instead of a wide sanding surface will make for precise cutting and reduce motor stress. However, you can't keep wheel coning, which will waste a lot of urethane. Also, you may have the heat / sandpaper wear issues I'm experiencing now.

[Chainmaillekid]

I dig the lathe design - real simple, just what we need. I really like the bearing+seized bearing design - achieves good alignment and minimizes the lathe's spinning components. genius. Standardization via internet components is a good move too.

The more I mess with my handheld-drill attachment design, the more I want to build a more lathe-like machine with a stable motor... flatspotted wheels are WOBBLY! I might try to build something like your design tonight while I'm waiting for the Leonid meteor shower (first peak tonight 0900 UT = 1am PST)

EDIT - I like your tool design too - using "passes" instead of a wide sanding surface will make for precise cutting and reduce motor stress. However, you can't keep wheel coning, which will waste a lot of urethane. Also, you may have the heat / sandpaper wear issues I'm experiencing now.

To keep coning...

That would only require a minor tweak in the design I think.
If I can find a way to easily make so you can change the angle of the tool mount in respect to the wheel.
I honestly didn't even consider it before :U

Also, if sandpaper is a problem...
I now files work well, as long as they are gritty enough.

[kraffft]

The thing is, the wheel and sandpaper get HOT - I had to replace the sandpaper about 4 times while doing the wheel.

The simplest thing would be to have a longer sanding block, so you're just lifting the gorilla tape, moving the sandpaper a little and taping it back down.

Maybe wet sanding? I've never seen coarse wet/dry sandpaper though (unless you count grip tape). Roughest at the store is usually ~220.

I really recommend the belt sanding belts too.. the grit lasts a lot longer and they're made to withstand overheating.

It's funny though because I never even would have tried sandpaper if it weren't for your design idea there.. but it does seem like the cheapest, most accessible option.

If you get in to using files and rasps (which I'm sure will work), It's always worth it with soft materials to use new/sharpened cutters.. because they'll stay sharp for a long time. Files get dull fairly easily, drawing them the wrong direction, and on too hard materials. It's also hard to find high quality files.. the hardware store ones are complete garbage compared to real machinists files. Wet cutting would work well with files too.. just dry them well afterward.

-Allow the sanding pipe to rotate when put in contact with the wheel, and use a friction resistance system to cause the wheel grinding

I've dimly thought of doing this somehow using a belt sander, or other power sander.. The wheel would need a very steady friction resist though.. something like fixing it to a hand crank could work..

-Cutting vs. Sanding: maybe an angled razorblade embedded into a PVC segment? Think of a potato peeler.. Hey - maybe a potato peeler would work!

For the cutter you really want something that's around 1/8" wide.. like a small chisel, or carving tool.. though for the same price you could get actual lathe bits (often just tiny carbide triangles).

This is roughly how I'd mount a narrow cutter:

Have a long bolt mounted through threaded holes in the same frame that holds the wheel, and just turn the bolt with with a wrench.. turning slowly as the cutter touches the wheel, and slowly going across the width of the wheel with each full turn.

The height adjustment could be partially where the washers pinch the cutter, and also having multiple bolt holes in the frame.

That's a tooth off a circular saw blade in the picture.. 24+ carbide cutters for $5 if you have an angle grinder to cut em up (my favorite power tool).

If you want to try shaping the full width of the wheel at once I'd go with a paint scraper blade, or a hand plane, though a razor blade might work if you grip it very close to the edge.. but any of those'll be slow and hot.

Motor would be coming from the Cheap $20 Harbor Freight drill.
I don't think we'll be dealing w/ the same torque loads here.

As long as the cutting surface stays small you might get away with this.. no trying to sand the whole width of the wheel at once though..

Something we haven't touched on yet is cutting speeds.. Electric motors have to spin at high rpm by definition.. and are almost always geared down for power tools.. giving them more torque..

The surface of a longboard wheel is a fairly large diameter to be cutting at high rpm.. and it gives you that much more leverage against the motor..

Urethane is fairly forgiving of high cutting speeds.. but you're needlessly creating heat and not removing material any faster after a certain point.. especially with sandpaper.

Once the wheel is fixed to the shaft, You tighten down the carriage bolt so the head of the bolt is pressed aginst the inner races of the bearing, holding it in place.

I like the one seized bearing design.. but maybe just a bolt-end/washer/nut fitting into the free spinning side instead of that round carriage bolt head? or at least something pointier.

Also.. it seems like you're relying heavily on the outer race of the seized bearing gripping the bearing seat..

[Chainmaillekid]

I purposfully am staying away from carbide cutting tools.

Thats what we typically use on our lathe, but urathane is too soft, and it has a tendancy to grab the tip, and occasionally break of the end, and launch it at dangerous speeds. It also likes to grab and jam.
This really limits the ammount of material you can take off in a pass.

With The motor... We'll I'll just have to get one and see.
But, when you're using it as a drill, typically you tighten stuff down to the point where it actually is going to stop the motor ( especially if you're tightening bolts. )

As far as relying too much on the outer race gripping the core...
This is basicly what we do with our lathe. Exept we use custom made aluminum peices instead of bearings.
( from 2:35 on to 3:15 )

YouTube - shop montage

You'll also see, that we do run it pretty slow.

I do agree on the carriage bolt thing, something pointier :P

[BAsports18]

I had a prettry large flat spot on one of my sergio sliders so i made a little appliance today using a hand drill with the chuck mounted into a 2x6 and then I used a wood file against a wedge shape. Horrible explanation but it worked ok. It took a while and the flat spot isn't entirely gone. Its similar to what ckpcw did

[atomicturtle462]

H2669 Hobby Lathe

[rodgon]

H2669 Hobby Lathe

lol WIN!

^_^

might have to get one sometime soon. have a bunch of messed up wheels that could have a second life.

[kraffft]

H2669 Hobby Lathe

($50, drill not included)

Nice.. That's some great Chinese pragmatism right there (check out a hardware store in China some time.. they rule). Same brand as in Chainmaillekids shop too..

But unless I'm missing something.. I've never seen a cheap drill that could be easily mounted in that bracket. There's usually no stationary collar between the chuck and the drill body. So you might either have to jury rig your drill or buy one for it.

And you're still going to want a 'seized bearing' mount for the wheel.. because it's hard to get a wheel centered on those centersets..

Here's the simple wood lathe trick I was thinking of (for perfectly squaring wheels/removing coning).. just putting a stop on your turning chisel:


It looks absurd.. but it's nice having the extra weight.


You want the stop and chisel to have three contact lines on the tool rest to make the lathing totally deskilled (and all the lines should be straight and square).


Also, here's a little trick if you don't have a seized bearing, and don't feel like waiting for glue to dry: just find a washer with a 7/8" outside diameter and tighten it down:


The single seized bearing method worked well with this wheel.. but there's plenty of wheels out there with very loose bearing fit that you'd either need to either shim or do something else with.


I really like how this thread is turning into a whole array of options for people to draw from.

[speshlspeclsteak]

looks like i gotta sieze up some bearings

[ckpcw]

Hey kraffft, forgive my ignorance but which way is the wheel spinning in your chisel pic? Counter-clockwise, correct?

The cheapo china hobby lathe is neat, but I don't have much faith in the stability/rigidity of the whole thing.

As for the seized-bearing method and looser wheel hubs - maybe we could use the hub ridges between the bearings. Off the top of my head, there are 2 main hub types - the usual one with three ridges, and the "striker" type with 6 ridges. Maybe a large hex nut could grab those ridges.. for the 3-ridge hub, grind down every other vertex of the hex nut?

I was also thinking that a nice sandpaper-based flushing tool like Chain's design would be good for brand new wheels to create "pre-wearing" a la Otang freeride. I love 80a 4Prez's after I've worn away the swirling, but at that point the wheel is already mad coned and worn a good 3 mm. Maybe a quick pass of Chain's tool could yeild a broken in, unconed wheel with ~1mm of wear..

This thread is getting cool!

[kraffft]

Hey kraffft, forgive my ignorance but which way is the wheel spinning in your chisel pic? Counter-clockwise, correct?

That's correct.. except it's not actually spinning in that pic.

Was meaning to make a note about spin direction/tool position.. but tried various angles in both directions with the sandpaper and all of them worked but also had their own dangers.. With hard cutters it's more finicky and dangerous.. but not too hard to figure out.. and soft materials are good to learn on.

As for the seized-bearing method and looser wheel hubs - maybe we could use the hub ridges between the bearings.

I like that idea.. you could similarly press fit a nut into the hubs that have no ridges.. better than further messing up loose bearing seats.


Going back to the carbide cutter issue.. I noticed similar intense grabbing when cutting the flatspot into that green wheel with a circular saw.. I imagine a steel circular saw blade would grab similarly though..

The interesting thing about the hard cutter mounted on a rotating bolt approach is that every time the cutter revolves, it's coming in for a new cut. It starts shallow and ends as deep as you have it set. This is different than your typical lathe pass where the cutter is at a fixed depth..

I'll put making a quick one of those on the to do list.. and if no one beats me to trying it out, I'll squeeze it in some time soon..

[Aaron]

Some points that work when cutting wheels on actual lathes. Stability is critical. The softer the wheel will benifit from being frozen. Use high speed steel cutter ground to razor keeness. Turning fast is better.
Fun stuff here but someones gonna put their eye out.

(added edit)
Something that may be cheap and work well (and safer) would be a fixture that clamps to the truck that allows for the accurate tracking of an angle grinder with and abrasive disk, parallel to the axle. Perhaps using a drawer slide having bearings. The disk would be positioned so that it contacts the wheel surface at a sweeping (approx 45 degrees) so that it both cuts and rotates the mounted wheel. This works great by hand on narrow vert wheels, this fixture would keep the cut within tolerance on wider wheels. Easily made for 20 bucks. Some clamps welded to the slide basically. Some kind of registration for the axle/board relative to wheel needs to be designed, and some kind of adjustment that maintains squareness. Very doable.

[SteveC]

I found using the reverse-lathe method worked ok. (bench-grinder, wheel on axle)
the main problem i found was if you let it get too-fast the heavy side of the wheel distorts outwards more than the rest of the wheel. it also sucks if it starts bouncing.

[BAsports18]

It's pretty complex, I wouldn't expect most people to understand it's intricacies...jk. It seems to work fairly well. it took a pretty big flatspot out of one of my sergios. Whats this I hear about freezing soft wheels? because I have 80a 4pres, 80a zigs and 83a otang freerides that I need to de-cone. Would it make any sense to reverse cone the wheels a little bit so it would take longer for them to recone?

[BAsports18]

I would forget to post the pictures...

[ckpcw]

So, schools out and I've had some time to think about this.. I've come up with a new design that might solve some of the problems with the flatspot removers we've made thus far.

Current design problems:

-Wheel bouncing. Biggest problem IMO. It makes sanding evenly very hard - the flatspots can actually get deeper in some cases. A solid mount is crucial, and this is why krafft's "wedge" method has been the most successful for me - the block is more stable and controlled. Even so, the block tends to "fall" into flatspots when too much pressure is applied, making the wheel worse.

-Drill torque. With my adjustment screw designs, wheel bouncing would require that the block be tightened firmly to start removing material. The drill would often slow, causing heavy sandpaper wear and poor/uneven urethane removal.

-Sandpaper wear. When the sanding area is small, the paper wears out fast. Another plus for the wedge method.


I believed to have solved these problems using springs, a movable sanding arm, and adjustment screws to adjust the maximum sanding depth. I'll get a picture up instead of trying to explain.

[ckpcw]

Double post!

Very simplified picture, but



Spring brings the sanding arm into contact with the adjustment screw (max cut depth). A drill spins the wheel's axle, and the sanding arm vibrates due to the uneven wheel surface

The adjustment screw is shortened in small increments once the sanding arm is no longer pushed back during rotation (all urethane at that depth as been removed).

Different spring strengths will need testing, but I think this can prevent excess torque on the drill and make the repaired wheels more uniform.

Also, with small adjustment screws on the sanding block (not pictured), the sandpaper wear problem can be solved. The screw will move the block radially along the arm. Wearing out? Twist a screw, and a fresh region is in contact with the wheel.

[LFP123]

wow this thread is really interesting.

[Chainmaillekid]

Bump!

The community project isn't finished :U

[afi1014]

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