Can I spin a flat head to plane it?

[ebinmaine 69,707]

I have about half a dozen cylinder heads that need planing at the moment for projects coming up in the next few weeks.

All Kohler engines. All flatheads. All aluminum.

Up until now I've been planing them by sticking a piece of sandpaper to a very flat surface and moving the head back and forth back and forth back and forth. Turn 90°. Repeat. Over and over and over until it's done.

As many of you know that's very time-consuming and... right now I'm fighting some physical issues that make it difficult to keep doing that for very long.

At some point in the future I'm going to pick up a larger belt sander for this type of work. Right now I don't want to spend any money until the barn project is figured out.

 

 

I had a thought this morning that maybe I could take a short piece of wood or metal. Put a solid bolt centered in it facing UP and two screws or bolts a few inches apart facing DOWN.

Loosely stick the down-facing bolts in between the cooling fins and slowly spin the cylinder head.....

By hand using a standard battery powered drill. Not on a drill press. Super slow. Sweep off the sandpaper every few dozen rotations.

 

 

Would this work? Why or why not?

 

[ri702bill 8,729]

7 minutes ago, ebinmaine said:

Would this work? Why or why not?

Eric:

MAYBE - I am not a fan of circular motion to get something flat - as in bodywork - you use a linear flat sander for that.

I AM a fan of the tried-and-true method with wet or dry sandpaper, used wet, and moving the head in a figure 8 motion.

Why not take a head from the "Parts Department" - one with a half stripped out spark plug hole - or some other less than desirable defect and have at it???

(In the old days at work we would have to do a sample of no less than 30 to gain confidence in the outcome of a statistical analysis study ....)

[ebinmaine 69,707]

2 minutes ago, ri702bill said:

Eric:

MAYBE - I am not a fan of circular motion to get something flat - as in bodywork - you use a linear flat sander for that.

I AM a fan of the tried-and-true method with wet or dry sandpaper, used wet, and moving the head in a figure 8 motion.

Why not take a head from the "Parts Department" - one with a half stripped out spark plug hole - or some other less than desirable defect and have at it???

(In the old days at work we would have to do a sample of no less than 30 to gain confidence in the outcome of a statistical analysis study ....)

I'd love to do a sample but I don't have any junk engines or cylinder heads right now

 

 

[gwest_ca-(File Mod) 11,176]

The outside of the head surface is going to see a lot more abrasive than the inside. Think of it like pulley sizes.

[wallfish 17,191]

I'm with Bill & Gwest. It might be difficult to apply even pressure as even a very slight deviation of the angle when spinning will make the edges uneven,

To save time start with a more aggressive grit and work your way down. (Down in size of the actual grit size but up according to the number grit).

Edited March 27, 2022 by wallfish

[ri702bill 8,729]

13 minutes ago, ri702bill said:

Why not take a head from the "Parts Department" - one with a half stripped out spark plug hole - or some other less than desirable defect and have at it???

I WAS going to say to grab the head off the Collasus Project as you would not be needing it anytime soon, but that would be downright COLD on my part!!

[ebinmaine 69,707]

5 minutes ago, ri702bill said:

I WAS going to say to grab the head off the Collasus Project as you would not be needing it anytime soon, but that would be downright COLD on my part!!

Hahahahaha.  

 

Those are two of them. 

 

 

 

[pacer 3,174]

Another approach that I saw some ... 40+ yrs? ago?

 

There was this fella and son that had built up a highly respected back yard machine shop (the kind you DO NOT see anymore) So my son had a little Datsun truck (yes, a real Datsun) that had a broken cam shaft. He had heard of this place so off we went to get the head ckd for any damage.

The old guy sez, yeah better let us ck it might have warped the aluminum head.....

 

So he goes over to this large - 36"? flat faced, adjustable ... abrasive? table. (like an oversized disc sander) and lays the head on the dead flat surface around the disc and turns it on and slides the head onto the rotating surface, constantly moving the head in different positions (like figure 8, etc). Do that for 15-20-25 seconds, slide the head off to edge flip it up to ck for high/lo places, put it back for a few more seconds and after bout 3-4 passes its flat all across!! $20 and we went home and put it back together.

[ri702bill 8,729]

39 minutes ago, ebinmaine said:

Those are two of them

Twins!!!

[JoeM 7,885]

EB color the surface with magic marker so you can see your progress. and check with a flat edge of course. One thing about it, you can always go back to the old way and fix it.

Your not going to remove that much material.

 

[Pullstart 63,529]

42 minutes ago, pacer said:

Another approach that I saw some ... 40+ yrs? ago?

 

There was this fella and son that had built up a highly respected back yard machine shop (the kind you DO NOT see anymore) So my son had a little Datsun truck (yes, a real Datsun) that had a broken cam shaft. He had heard of this place so off we went to get the head ckd for any damage.

The old guy sez, yeah better let us ck it might have warped the aluminum head.....

 

So he goes over to this large - 36"? flat faced, adjustable ... abrasive? table. (like an oversized disc sander) and lays the head on the dead flat surface around the disc and turns it on and slides the head onto the rotating surface, constantly moving the head in different positions (like figure 8, etc). Do that for 15-20-25 seconds, slide the head off to edge flip it up to ck for high/lo places, put it back for a few more seconds and after bout 3-4 passes its flat all across!! $20 and we went home and put it back together.

The tool and die shop I worked at had a very large surface belt sander.  I ran a few heads across that in the day.  It worked so well!

[Handy Don 13,080]

I agree with the stationary belt sander with gentle pressure and a very fine belt (200 or higher). They can remove a lot of material quite quickly.

 

Keep an eye on CL for a 4" or 6" belt/disk combo with an internal motor (these are more compact that those with the separate motor). An old Craftsman, Delta, or similar (avoid the HF Chicago Electric and other budget units--weak motors with poor bearing and castings). I just got a Craftsman 4" belt/6" disc that was identical to the Delta of the same vintage. Going rate is around $50-90.

Edited March 27, 2022 by Handy Don

[WHNJ701 4,165]

for all the heads covers I ever sanded, I spray paint them flat black, and sand with a piece sandpaper with a glass block.  All the ones I did rarely took more than 10 minutes of hand sanding to get them flat again.  Plus the you have the head gasket.  Yes I try do things right but I am  also not building a spec airplane engine either.

[Maxwell-8 4,366]

Back and forth is how I do it

 

Safest in my opinion

 

Edited March 27, 2022 by Maxwell-8

[WHNJ701 4,165]

Forgot to add in my last post, I was taught to sand on 45 angles

[ebinmaine 69,707]

26 minutes ago, jabelman said:

for all the heads covers I ever sanded, I spray paint them flat black, and sand with a piece sandpaper with a glass block.  All the ones I did rarely took more than 10 minutes of hand sanding to get them flat again.  Plus the you have the head gasket.  Yes I try do things right but I am  also not building a spec airplane engine either.

 

I've used a piece of tempered glass on a towel on a table. 

This time I'm using a piece of flat steel. 

What grit do you start and end with?

I've usually done 80 til close then 120, 180, 220, 400. 

 

I've never been less than 45 minutes between setup, switching paper and cleanup. 

 

The head I just got done this morning is the worst one I've had yet. 

It was out pretty badly on 2 opposite corners. 

 

Been using 120 grit (no 80 on hand). 

80-100 fore n aft strokes. Turn 90⁰. 

Repeat. 

It's been at LEAST 2-2.5 hours work on this one. Off and on for weeks. 

Several thousand strokes for sure with no exaggeration. 

 

 

This morning I finally switched to 80 grit for awhile and obviously that worked much faster.  

Then 220.  

Enough for that one ...

 

 

I'd bring them to a machine shop but all the local places want 50 to 75 per head. Not happening.  

[RubyCon1 63]

 

[ri702bill 8,729]

53 minutes ago, ebinmaine said:

'd bring them to a machine shop but all the local places want 50 to 75 per head.

Time and space is money in a shop.

[bc.gold 3,403]

The flat lap, motor is attached to a cup inside an eccentric weight attached to the motor shaft creates the motion.

 

Edited March 27, 2022 by bc.gold

[ebinmaine 69,707]

56 minutes ago, RubyCon1 said:

 

Appreciate the link. 

 

That's a similar method to what I've been doing but he did figure 8s and I do straight strokes and turns. 

 

That head in the thread was allegedly done 120 strokes or so. 

 

Mine....

1 hour ago, ebinmaine said:

Several thousand strokes for sure with no exaggeration. 

 

 

 

As stated in my original post:

5 hours ago, ebinmaine said:

right now I'm fighting some physical issues that make it difficult to keep doing that for very long.

 

I don't mind using a hand plane method normally. 

 

 

45 minutes ago, ri702bill said:

Time and space is money in a shop.

Oh yes absolutely. 

 

My thinking there is that if I'm gonna pay someone -/+$300 I'd sure as shootin' go buy a nicer belt sander and gladly justify the purchase. 

 

[ri702bill 8,729]

4 hours ago, ri702bill said:

I WAS going to say to grab the head off the Collasus Project as you would not be needing it anytime soon, but that would be downright COLD on my part!!

I know it was low hanging fruit, but I could not resist ....

[ebinmaine 69,707]

2 minutes ago, ri702bill said:

I know it was low hanging fruit, but I could not resist ....

Nuttin' wrong with that.  😀

[Ed Kennell 39,733]

I just picked up two Craftsman oribotal polishers for a buck at the auction.       Now I'm thinking....epoxy a piece of glass to the polisher, tape on the emery cloth, clamp the head in the vise and have at it.

[Jeff-C175 7,203]

43 minutes ago, Ed Kennell said:

I just picked up two Craftsman oribotal polishers for a buck at the auction.       Now I'm thinking....epoxy a piece of glass to the polisher, tape on the emery cloth, clamp the head in the vise and have at it.

 

Why not just place the orbital sander polisher on top of the head and move it around? 

 

 

Edited March 27, 2022 by Jeff-C175

[Ed Kennell 39,733]

43 minutes ago, Jeff-C175 said:

 Now I'm thinking

Now Jeff is thinkin.