# How To Hold This Part In Lathe?



## WesPete66 (Jun 5, 2016)

I have an Atlas TH54/QC54 lathe, with basic tooling. (3 & 4 jaw chucks, face plate, steady rest, milling fixture etc) I have a part that I would like to face flat, but am not sure if I can do it with what I have available. The part is a cylinder head for an antique engine, about 6.5" dia, irregular shaped, with four thru-holes. I'd like to clean up the mounting/gasket surface as it was badly rusted.  There is no way I can hold the part in a chuck, so my thought was to use a face plate, placing spacers to support the part on four bolts. The problem is that the bolt heads would be sitting right where I want to face the part. So is there another method to hold this? Something other than a bolt to hold the part?


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## Ulma Doctor (Jun 5, 2016)

i know it may be a risky proposition,
but you could possibly make a support fixture that used the valve guide holes with brass studs (or other soft studs) and a holding plate, to tighten the head up to it's spaced out position on a faceplate.
you could utilize some studs that don't protrude all the way through the head as an extra measure of security, when machining the head flat.

the only other choice i can think of is a very large swing'd lathe that you could put the whole head in the chuck's center bore and hold it with a 4 jaw around the diameter. 

you could always *scrape* it flat too...
i'd be happy to do it (scrape it) for you.


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## f350ca (Jun 5, 2016)

I like Mike's idea of bolting it to the face plate through the valve guides, steel bolts shouldn't hurt as there'd be no movement. Then use 4 bolts with nuts acting as jack screws into the head bolt holes. With them you can level it up.
No spark plug hole, is it off a diesel?

Greg


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## chips&more (Jun 5, 2016)

You could MAYBE try a belt sander of adequate size and with a good flat platen. I can’t stress the maybe part enough. Finesse would be paramount in this operation. One bad move or selection in any part of this idea and it could be all over.


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## Charles Spencer (Jun 5, 2016)

You could put it in your milling fixture and use an end mill.  Of course that would be a pain because the fixture probably doesn't have sufficient travel.  You would have to re-position it during the operation.  Still it could work if done with care and judicious use of a dial indicator.


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## Uglydog (Jun 5, 2016)

Is it cast iron?
If so, she might be scraped in. 
I've heard of high compression automotive race engine heads being scraped in so precisely that the need for head gaskets is avoided, and thus no gasket failure.

Steel can also be scraped, but it's difficult due to hardness.

Daryl
MN


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## WesPete66 (Jun 5, 2016)

Thanks for the good suggestions!  This is from a hit & miss gas engine using an igniter (battery & coil ignition).  and it is cast iron.
Would concrete anchors be acceptable? I would put the anchor end into the head's thru-hole, and bolt it to the face plate?
Thanks again & keep em coming!


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## mksj (Jun 5, 2016)

Per Ulma Doctor,

So something like: Starting out with an aluminum round or square plate (something like 1/2" by 7 - 8") to use as a mount in the lathe chuck, mill or saw out the section on the mount for the head mounting bracket on the head. Turn 4 posts that will snugly into the head mounting holes so they have a shoulder on both sides (this will provide better stability and set a fixed distance between the head and plate) and fasten the other ends into the aluminum plate (thread the standoff or bolt through). The length of the four posts between the shoulders need to  be slightly higher than the valve guides and allow enough space behind the mounting plate for the head mounting bracket, so about 2.5" between the mounting plate and head bolt holes. Drill two holes in the mounting plate to align with the valve guide holes, use washers with bolts extending through the valve guide and  into the aluminum plate. These will tension the head to pull it down against the 4 posts. The 4 posts just act to stabilize the head. I would make sure on the bolts there is no thread up against the valve guide, you do not want the thread to damage the guide if there is any movement.

It looks like the two valve guides and 4 head mounting holes are all symmetrical around the center of the head, so you could just pull off the measurements and build a  jig to hold the head. You may want to use a 4J independent chuck if you need to center the milling area. If using a square plate in a 4J, may want to use some spacers between the chuck and the mounting plate so it stays parallel when turning. Low speed, sharp cutter, multiple light passes.  Sometimes I mock things up with wood to check clearances.

Other option would be to use a mount in a rotary table on a mill.


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## Techie1961 (Jun 5, 2016)

Interesting part especially since the combustion chamber is proud of the gasket surface. You won't be able to use a belt sander and a milling machine will be tricky as you will have to creep up on the ridge and not cut into the chamber.

I would be inclined to bolt a round piece of aluminum to the combustion chamber side with two bolts through the valve guides. Then you can chuck the aluminum block and indicate the surface as well as the combustion chamber diameter. As long as the lathe is large enough, you can then come around from the chuck side to resurface it. I hope this makes sense.


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## timvercoe (Jun 5, 2016)

Techie1961 said:


> Interesting part especially since the combustion chamber is proud of the gasket surface. You won't be able to use a belt sander and a milling machine will be tricky as you will have to creep up on the ridge and not cut into the chamber.
> 
> I would be inclined to bolt a round piece of aluminum to the combustion chamber side with two bolts through the valve guides. Then you can chuck the aluminum block and indicate the surface as well as the combustion chamber diameter. As long as the lathe is large enough, you can then come around from the chuck side to resurface it. I hope this makes sense.



Would't surfacing the rusted part then change the combustion chamber?  Is it a diesel?  What about Valve to piston interference?  Seems to me that what ever was removed from gasket surface would then need to be made up with gasket thickness or equal amount be removed from combustion area.  

Now for you original question, how to hold?  I think a lathe would be the best.  I agree with a fixture, or a large enough lathe to use a 4 jaw chuck. You may still have to make a fixture or fixture pieces to hold in chuck.  I find when puzzled by a set up that sleeping on it usually provides the answer.  

I just read techie1961's post again.  That is a great idea, if your machine is big enough or make a mandrel and a fixture and hold it at the tailstock end and surface away.   

Tim


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## jpfabricator (Jun 5, 2016)

If theres no blowby, why surface it. If you do surface it use copper sheet metal as a shim and gasket.

Sent from somewhere in East Texas by Jake Parker!


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## Bill Gruby (Jun 6, 2016)

Because of the proud combustion chamber you will have to center that part perfectly to face it off. Nike is spot on with using a fixture and the faceplate. MO.

 "Billy G"


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## Kernbigo (Jun 6, 2016)

if it is not to bad you can lap it on a lapping  plate


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## tq60 (Jun 6, 2016)

Forget about using the lathe directly.

This is low compression engine so perfection not needed.

You can make a lapping plate so to speak.

Find a chunk of flat round plate and Chuck it in the lathe and make a female mating part that would fit the head.

Next place lathe in back gear and load the part with lapping compound and hold the head against it.

Short periods then test.

Does not need perfection as the gasket will take care of that.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk


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## Bob Korves (Jun 6, 2016)

First, cause no harm.  You cannot just go to a store and buy a new head if it is damaged during the surfacing operation.  Scrap the head, scrap the engine, perhaps.  Mounting it on a face plate can be dicey and it scares me for an irreplaceable part.  Kernbigo just beat me to it, but i would lap the head on a flat surface using sandpaper and a surface plate, plate glass, or something KNOWN to be FLAT.  You can take your time, and check it with a good straightedge as you go.  The gasket will conform to some amount of imperfection at the joint, so don't overdo the surfacing operation.  Take your time, do it carefully, make sure to hold the part low down so it stays flat and does not have a tipping component to the lapping, ruining the flatness.  Emphasize flat, not pretty, and go no deeper than necessary to make the gasket seal.

Edit:  TQ60 beat me to it as well.  I need to learn to type faster, or quit eating breakfast while I do this...   8^)   I would not use the rotary lapping method for this part.  More dicey, less likely to stay flat.  You could also take the part to a machine shop and have it Blanchard ground, but where is the personal satisfaction in that?

Second edit: Missed that the center stands proud of the gasket surface.  I would still lap it, just on a flat donut shaped plate with abrasive paper.


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## juiceclone (Jun 6, 2016)

?Use appropriate fixture and studs as mentioned, but then use the tailstock with adapter and live center as necessary to hold in place?


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## Ulma Doctor (Jun 6, 2016)

just a fyi,
shaving a couple thousandths off the heads' thickness won't have any catastrophic consequences, i'm sure the valve to piston clearance is more than sufficient.
you may even get the added boost of a higher compression ratio, by decking the head!!!
if you port match and polish the head on that lil beast, you may get a horse and a half or 2 to the flywheel!
be sure to take a movie of the running engine, i'd love to hear it!


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## WesPete66 (Jun 7, 2016)

Thanks for all the good info!
Just a few comments on what I'm seeing above.. 
It doesn't show the extent of the rust erosion in the pics. It may be .060 deep in some areas and is beyond lapping, but that was a good idea. Actually the valve stem had rusted clear through & left the valve head laying in the cylinder where I found it..
I'm not trying to get a perfect surface. Heck I'll be quite happy if I can get a continuous ring of flat surface inside of the bolt holes. Then the gasket can do its job.
These engines have loads of space between the valves and piston, like maybe an inch plus.
I do like Techie's idea of mounting it faced towards the chuck. I will look closer at that concept, but I don't know if my lathe can handle that..
Thanks again & keep them coming..


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## skinny_jim (Jun 7, 2016)

This is my first forum post, ....... but hear goes .... if you were to use some type of tapered plug in the bolt holes and have these expand as you tighten them up that would hold the part to some sort of backing arrangement which could be secured in a 4 jaw or faceplate. The projection on the back looks like it is about 4" long would cause a lot of interference and is probable the reason you can't hold it in a 4 jaw chuck.  This type of arrangement would stick out about 6" which is a lot of overhang. I would use the tailstock to support the workpiece with some type of plate with a centerdrill hole to sandwich the part between the chuck and the tailstock. This should give the set up enough rigidity to machine the face. A milling machine set-up might be easier but you asked how to do it on a lathe. An alternate might be to set some type of mounting pins in the 4 holes and pull the part down using a bolt through the valve stem holes. ......... or you could use some square stock and pins with a light press fit into the 4 bolt holes for the backing arrangement.  Either set up needs the tailstock for support. Good Luck!    


Jim


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## bosephus (Jun 7, 2016)

Air cooled with non water to leak ,   I think in would spray it he sealing surface with about 6 heavy coats of copper spray  a gasket and use a copper head gasket and call it good


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## Tozguy (Jun 7, 2016)

WesPete66 said:


> Thanks for the good suggestions!  This is from a hit & miss gas engine using an igniter (battery & coil ignition).  and it is cast iron.
> Would concrete anchors be acceptable? I would put the anchor end into the head's thru-hole, and bolt it to the face plate?
> Thanks again & keep em coming!



Concrete anchors is a great idea. I bet you could make that work.


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## WesPete66 (Jun 7, 2016)

water cooled Bo, that's what caused the rust erosion.. the cooling water directly contacts the cast iron of the head through slots in the gasket.


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## barnett (Jun 7, 2016)

Is that an Associated or United head ? looks like it, I have a spare one i think, send me some info on the engine. I would be careful with the concrete anchors, it could expand enough to possibly crack that cast iron. 

Tom


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## bosephus (Jun 7, 2016)

Gotcha , if the bulk of the pitting is where the gasket relief  is I would ignore that pitting and look strictly at the sealing surface .
You might be surprised at how rough it can be and still seal up on a low compression engine.

Another thing to consider before getting to crazy with re surfacing the head  is what you will need to do to correct the valve train afterwards.   Removing  .040 -.060 doesn't seem like a whole lot but depending on rocker set up and the amount of  adjustment if any you might be looking at lenghening or shortening your push rods to corrdct the geometry


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## Dave Smith (Jun 8, 2016)

My idea would be to thread the bolt holes and use bolts on the back side to secure it to the faceplate---having the bolt holes threaded shouldn't be a problem when reassembling -----may only need to thread two opposite holes, but doing all four may be easier on mounting and shim adjusting to faceplate for accuracy---Dave


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## FLguy (Jun 8, 2016)

Dave Smith said:


> My idea would be to thread the bolt holes and use bolts on the back side to secure it to the faceplate---having the bolt holes threaded shouldn't be a problem when reassembling -----may only need to thread two opposite holes, but doing all four may be easier on mounting and shim adjusting to faceplate for accuracy---Dave


Like this idea!! Seems to solve a lot concerns.


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## TOOLMASTER (Jun 8, 2016)

ja jus run der belter sander tingy over it a cupple times


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## cjtoombs (Jun 9, 2016)

One thing I thought of is potting the back end of it in polyester resin or epoxy, then holding it by the face end in the lathe chuck and truing up the potted end, turning it around and facing the surface while holding it with the potted end.  You could then just bake the potting compound off.  For a part that size, it might be kind of an expensive one time use jig, but might save a lot of time over some other methods.


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## Andre (Jun 9, 2016)

Uglydog said:


> Is it cast iron?
> If so, she might be scraped in.
> I've heard of high compression automotive race engine heads being scraped in so precisely that the need for head gaskets is avoided, and thus no gasket failure.
> 
> ...



I think laminated copper head gaskets can be used for high compression performance engines, and now a lot of import guys actually use O-rings for special forced induction applications.

Steel is awful to scrape....those rolls of metal stick in you and by the time you're done stoning burrs off you've ground a hole to china.

To hold the cylinder head, I wonder if you could put a cardboard sleeve over it, fill the whole thing with plaster, then chuck up the plaster in the 4 jaw and use the tailstock to keep the head in place. Basically making a negative of the head, similar to a chamber cast in gunsmithing.


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## Dave Smith (Jun 10, 2016)

I think you are thinking too complicated for less than a one hour simple facing-----5 minutes to thread the bolt through holes--then using threaded rods and nuts to carefully secure it to the faceplate accurately may take 45 minutes---then facing the surface shouldn't take more than 10 minutes---and 5 minutes to remove finished part from the faceplate----think simple---Dave


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## Chris H (Jun 10, 2016)

Is the gasket sealing the water cooling, or is it sealing the combustion chamber?  With a projected (proud) chamber, my understanding was that it was designed that way to keep from stressing the gaskets of the time, making the mechanical iron/steel parts do the bulk of the sealing.


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## CraigB1960 (Jun 10, 2016)

I like the suggestion(s) to thread the bolt holes and using them for mounting to a faceplate.

Another way would be mount on a mill and use an automatic boring head.

I can't tell from the photos, but is the proud part a fire ring?  If so, be careful how much you take off the gasket surface, you might want to check all your clearances once done.


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## WesPete66 (Jun 10, 2016)

Chris,
The projected area doesn't seal anything, maybe protects the head gasket from direct exposure to the ignited fuel.
The head gasket seals both the cylinder/compression, and the cooling water.

I'm planning to build a steel base plate to mount the head onto, since the bolt spacing is just a bit too big to fit on my lathe's face plate.


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## Keith Foor (Jun 12, 2016)

_I wrote this before reading ALL the posts... didn't just delete because the comments at the bottom seemed to fit this situation very well._


Here's  a complicated way to do it but a workable one.  First open to boltholes up to the next thread diameter... meaning if the holes are slightly less than 5/16 drill them to that then thread for 3/8 if larger then do the same thing getting them to a common thread size.  Once you have them threaded you are going to bolt the head to a faceplate through the back side of the plate.  Getting it squared up may be the only real issue and you may have to make sleeves to run from the top of the head to the faceplate to get a good square mount for it.  Once you have that done just face it off taking light cuts.  Since the bolts for the head come down through the head, having the holes slightly oversize and threaded should have no effect on mounting the head back on the engine once you are done.  There is an interesting thing about being a home shop hobby machinist.  It's like a gunsmith once told me, you are typically faced with mounting or making a part that someone 100 years ago filed out of a piece of spring steel.  There is no template, design drawing or print giving you direction for the order of machining operations to complete the project.  You simply wing it. 

Hobby machining is like that.  And in truth it's why many folks steer clear of the hobby.  There are a ton of yet to be discovered lathes and mills sitting in garages and barns that hardly got used because of projects like this head.  The facing part is EASY.   Mounting that on a faceplate or in a chuck is the hard part... It may take hours,  facing it off should only take about 10 minutes.


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## Chris H (Jun 13, 2016)

Thanks, Wes!


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## kwoodhands (Jun 20, 2016)

WesPete66 said:


> I have an Atlas TH54/QC54 lathe, with basic tooling. (3 & 4 jaw chucks, face plate, steady rest, milling fixture etc) I have a part that I would like to face flat, but am not sure if I can do it with what I have available. The part is a cylinder head for an antique engine, about 6.5" dia, irregular shaped, with four thru-holes. I'd like to clean up the mounting/gasket surface as it was badly rusted.  There is no way I can hold the part in a chuck, so my thought was to use a face plate, placing spacers to support the part on four bolts. The problem is that the bolt heads would be sitting right where I want to face the part. So is there another method to hold this? Something other than a bolt to hold the part?
> 
> Use studs instead of bolts. The studs will keep the head aligned and either a live center or live chuck ( rolling chuck) against the head .After you clean up as close as possible to the live center point, remove the head and clean the area where the point touched by hand.Even if the studs are proud of the head,face them as you do the head itself.
> 
> mike


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## tq60 (Jun 21, 2016)

I stand on my suggestion to make a mating part to lap in but I add epoxy.

Get some exhaust or muffler repair epoxy and buff head clean with wore wheel then clean it again.

Scrub with acetone then mix batch of epoxy and thin with acetone and pour it in the mating area and scrub it into all pits with brush then let it cure for a week.

Cut out a sand paper ring same as gasket of wet dry and with the lapping plate hold all in running water and lap off the epoxy and you will have a perfectly flat Un - pitted surface.



Sent from my SAMSUNG-SGH-I337Z using Tapatalk


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## WesPete66 (Sep 7, 2016)

Just thought I'd follow up on this post to show how this project played out..  Thanks to all for the tips & suggestions!!
I bought a rectangular piece of steel plate large enough to take the (tapped) hole pattern, and to allow the chuck jaws to clear the post on the part. Also four threaded studs with nuts. (Surprising how UN-flat a piece of bar stock can be.) 


	

		
			
		

		
	
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The two tapped holes in the center are where 2 bolts will pull the part against the stud spacers. 




	

		
			
		

		
	
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Next was to clamp the assembly in the 4-jaw.  And with much trial & error, got it dialed in to what seemed to be centered and with the face running basically flat and true. (it was hard to tell as it was eroded away so badly)  The tail-stock was used to support the part & keep it seated against the chuck. 






I carefully started the lathe & ran it at a slow speed, and using cross feed.  I was surprised at how easily the tool took to the cast iron. (ok this was my first time working with cast iron.. and first chance to use the power cross feed.)  I thought maybe the holes would cause problems, but no problem. Several light passes later and the part looked great, even better than I thought it would do!  I didn't get all the pitting out, but it did clean up in the areas where the gasket seats and does its sealing. 
This job turned out so well that I quick disassembled my antique water pump (which was leaking at the end gasket) and turned the face on its end gland too! It worked out great also, no more leaking!
So I'm happy with the results.  Thanks to all for the suggestions that helped me complete this job!!
Wes


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## kd4gij (Sep 9, 2016)

Nice work. " I love it when a plan comes together."


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