6" Belt Sander to "Mill" Heads and Pistons

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bob58o

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I see people on the interweb using Belt Sanders to "Mill" cylinder heads and "Cut" piston tops flush with the deck.

With practice and even pressure, can a "good-nuff" job be done with the belt sander?
I'm talking about a $200 6" Belt, 9" disc combo sander.
https://www.harborfreight.com/6-in-x-9-in-combination-belt-and-disc-sander-61750.html

If sanding a cylinder head for increased compression, would you want a thicker fiber gasket (opposed to a thin metal one)?
 

kevbo22

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I suppose you could make that work. But obviously nothing will beat a mill with a fly cutter for that operation.

If you are going to spend that kind of money, might just want to look at getting a mini mill. wait for a 25% off coupon and get the harbor freight mini mill

https://www.harborfreight.com/two-speed-variable-bench-mill-drill-machine-44991.html.

I bet you could even find a used mini mill x2 on craigs list for $250.

You have any video of a belt sander "milling the head"?? I'd like to see that if you do.
 

kevbo22

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How do you know how much you took off?

You would have to use a dti to see how much you took off. My question would be how do you take off say a uniform 30 thou?? I dont see it being a very accurate way of doing it personally. But thats not saying that it wouldnt work. I have no idea if it would be accurate enough or not.
 

Texan

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We had a older one at my job that they since got rid of. It was older but stout. It was maybe like a 16" or bigger disc.

Prototype parts are sometimes hand made/modified for timesake. With a new disc and the table squared up holding a dimension or flatness under .005" was easily possible. Sometimes jigs were made to be more accurate.

We are experiencing what is called 5S at work. It is part of Lean Manufacturing theory. Anyways, part of the 5S is getting rid of stuff that isn't used as often as everyday things. I don't like it. Well that belt sander was a victim of 5S. They didnt even ask the people who actually used it.
Somebody is always looking for something at work, and usually the answer is "They 5Sed it". :mad2:
 

ezcome-ezgo

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Wonder if HF will ever carry a decent bandsaw? Not a portable one, one like that sander, floor stand.
 

mckutzy

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Fricken 5s BS.... Had a bunch of 5s nazi inspectors at our factory I used to work at..
Had a lifer member get written up and almost fired for "not obeying the rules", started by slinging his jacket on his station chair in a hot day, then they started to pick at everything..
Frickin rediculose...
Sorry... 5s flashback...
I however got a bunch of hand tools as per the cull... The only good thing...
 

supermanotorious

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not to stay too far from topic but my department is under going a "lean transformation" and it is BS, I work in the investment field and there are so many "special" situations that lean just doesn't work with

anyway I learned about the HF mill thru this thread, interesting, and yes I suppose you could "mill" your cylinder head on a bench grinder, I made a part on a bench grinder that had to be accurate to .001" in an engineering class at the USMMA
 

bob58o

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If somebody went with a mini mill, what types of accessories would also be needed besides some type of vise to put on the table.

I suppose with a mini mill, a fly-cutter shouldn't be a large diameter and multiple passes would be needed.

I have no idea how to use a mill. Anybody got an idea what tooling would be needed to fly-cut a 4" x 5" aluminum cylinder head.

I guess something like this with a 1/2" shank, but what length cutting bit can be used?
Could I use something that is 5" and make a single pass?

And don't those cutting tool bits need to be shaped - or can you just use them as them come?

This comes with a 1-3/8" head and 5/16" bit. I think I've read the bit included can do 70mm (2 passes is5.5"). So would that get the job done?
https://www.ebay.com/itm/Steelex-M1...m=252444867175&_trksid=p2047675.c100005.m1851
 

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kevbo22

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Most mini mills use a r8 collet, so you would need a r8 collet set right off the bat. You can get a decent r8 collet set on amazon for about $50.

https://www.amazon.com/13-Precision-Round-Collet-Set/dp/B007HNYXXI

maybe some work holding fixturing you will eventually use??

https://www.harborfreight.com/58-pi...ch-16-nc-studs-1-2-half-inch-clamps-5952.html

a starter end mill set

https://www.harborfreight.com/20-piece-titanium-nitrade-coated-end-mill-set-5947.html

you could get some fly cutter or face mills as well.

A parallel set

https://www.harborfreight.com/20-piece-parallel-set-789.html

There is a ton of tooling for a mill. And once you get a mill, you will start finding yourself in a project where you end up purchasing more tooling.

I run a tormach 770, Dont even ask me how much I have into tooling, fixturing, and clamping lol.

EDIT: You dont have to use a fly cutter to do this. I mean a end mill would work just fine, it would just take more passes to complete the operation. You should be able to use the face mill right when you get it. Some people sharpen old tools, some just replace the carbide (https://sherline.com/product/7622-replacement-carbide-insert-for-7620-fly-cutter/), and some just purchase a whole new face mill or fly cutter. Its up to you.

The fly cutter set you posted would be fine.
 

anickode

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I think you could actually be pretty successful with a stationary belt sander if you used a very fine grit belt (like a 280 or so?) And wet it down (assuming that won't ruin the sander). It would remove material slowly, allowing you to turn the head as it grinds, lessening the chances of just destroying your head.

It would be more like power lapping than milling I suppose, but certainly faster than doing enough manual lapping to remove a significant amount of material.
 

kevbo22

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I supopose if you are only going to use a mill for 1 purpose only, and that purpose is to use a 1/2" shank fly cutter to mill a head. You could purchase just one fly cutter and 1 collet, a workholding fixture set and save a lot of money. These 3 things would work for that purpose.

https://www.amazon.com/1-2-R8-Round-Collet/dp/B0007TXLSC

https://www.amazon.com/Threads-T-slots-Machine-Tables-Finish/dp/B077BGX9TK/

For instance this guy is using only 2 t nuts fixing a work holding plate to the table, and then bolting his work piece to the plate, then milling it with a fly cutter.

https://www.youtube.com/watch?v=SAwLR0YFkSw

---------- Post added at 03:19 PM ---------- Previous post was at 03:14 PM ----------

Wonder if HF will ever carry a decent bandsaw? Not a portable one, one like that sander, floor stand.

Like these:

https://www.harborfreight.com/1-hp-7-inch-x-12-inch-hydraulic-feed-metal-cutting-bandsaw-97009.html

https://www.harborfreight.com/horizontal-vertical-metal-cutting-bandsaw-93762.html

Or are you talking about a vertical one?
 

65ShelbyClone

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Specialized belt sanders have been used for surfacing automotive heads for a long time, so the concept is sound enough. The main determinant of flatness will be the steel plate behind the belt.

https://www.google.com/search?q=bel...-JrdAhWSLnwKHe4nCFcQ_AUICygC&biw=1600&bih=749

Even if it doesn't come out adequately flat, it's not that much extra work to flat lap the head on a piece of sturdy glass (a real surface plate is better though).

A pair of $20 calipers would be adequate for measuring how much was removed. Most utility engines seem to have a valve cover gasket rail that is parallel to the deck and easy to access.

If somebody went with a mini mill, what types of accessories would also be needed besides some type of vise to put on the table.

I suppose with a mini mill, a fly-cutter shouldn't be a large diameter and multiple passes would be needed.

I have no idea how to use a mill. Anybody got an idea what tooling would be needed to fly-cut a 4" x 5" aluminum cylinder head.

I guess something like this with a 1/2" shank, but what length cutting bit can be used?
Could I use something that is 5" and make a single pass?

And don't those cutting tool bits need to be shaped - or can you just use them as them come?

This comes with a 1-3/8" head and 5/16" bit. I think I've read the bit included can do 70mm (2 passes is5.5"). So would that get the job done?
https://www.ebay.com/itm/Steelex-M1...m=252444867175&_trksid=p2047675.c100005.m1851

I only have experience with full-size mills so my first concern with a mini mill would be machine rigidity. The leverage and cutting pressure on a flycutter will definitely test it, especially if the cutter has a radiused edge for a smoother finish.

There again, it would be perfectly fine to make many passes with a smaller flycutter or flat end mill and then lap the head if necessary. BTDT. It will already be close to, if not usable if the spindle is level and square.

We are experiencing what is called 5S at work. It is part of Lean Manufacturing theory. Anyways, part of the 5S is getting rid of stuff that isn't used as often as everyday things. I don't like it. Well that belt sander was a victim of 5S. They didnt even ask the people who actually used it.
Somebody is always looking for something at work, and usually the answer is "They 5Sed it". :mad2:

not to stay too far from topic but my department is under going a "lean transformation" and it is BS, I work in the investment field and there are so many "special" situations that lean just doesn't work with

I think when Lean actually works, that's the exception.

My condolences to you guys. Last place I worked had this quality engineer that 5Sed the inspection lab I alone was running. Tape outlines on the floor, labels everywhere, a room schematic with workflow diagrams, the whole bit. All that 5S and Lean stuff is madness. The concepts are nice if you're a robot, but implementation is usually disaster-scale and the people who push it preach like cult leaders. The indoctrination materials read like fascist propaganda. :backtotopic:
 

Nosandwich

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Wonder if HF will ever carry a decent bandsaw? Not a portable one, one like that sander, floor stand.

IDK, I'm pretty darn happy with mine. I cut wood, but I made a spacer to raise the head enough to resaw 2×12' s and it worked pretty well. Of course, when you don't have a lot of cash, you tend to use what you have, make it work, and be happy .
 

Joe-405

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I used a right angle grinder and sanding disc on my piston in the minibike.

Worked perfectly fine.
 

bob58o

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I used a right angle grinder and sanding disc on my piston in the minibike.

Worked perfectly fine.

I remember from the build, but would you trust something like that on the head gasket sealing surface. A rough piston could possibly cause detonation issues, a wavy piston might cause cause flame propagation issues (probably not) but a leaky head gasket would be different. Since often we use thin metal gaskets, instead of thick composite ones - I assume flatness is of utmost importance.
 

Joe-405

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I would only trust it on a piston. And I used super fine grit sandpaper on a flat surface to finish it up. It was back to polished smooth after I was done. I only took the raised lip off the top of the outside and matched it to the center. It was flush with the top of the cylinder with the long rod from arc. Seem to make more power with more rod length. It’s kind of a race car thing I remembered from using.
 
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