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Mill cylinder head/seat work without pilot

General engine tech -- Drag Racing to Circle Track

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SchmidtMotorWorks
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Re: Mill cylinder head/seat work without pilot

Post by SchmidtMotorWorks » Wed Jan 22, 2020 10:40 pm

Valve seat 1 wrote:
Wed Jan 22, 2020 9:44 pm

Doing heads on a CNC Is not cost effective if your going to use 3 or different cutters. However a form tool with all the angles built in is . We get them made all the time for different aero space jobs at the shop where I work.
They aren’t overly expensive either. Just make sure you ramp the on and ramp off the seat after the cut with a spring pass as well.
Pass as well
It depends on your goal, if you are satisfied with a revolved shape a shaped insert will be fine.

If you want a shape that is different in the center of the chamber than it is at the chamber wall, then a small ball cutter is required.
A modern CNC with a high rpm spindle, fast and accurate feed could cut a seat of any shape in less than a minute. The machines we had in the 90's seemed like about 30 minutes for a 4 valve V8 head. A modern machine would be easily 5 -10 times faster.
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Re: Mill cylinder head/seat work without pilot

Post by Valve seat 1 » Wed Jan 22, 2020 11:03 pm

There are many different shaped inserts some with a radius in the bowl ect... However using a ball to single point or penciling the shape always leaves a cusp from the step over . Maybe I’m misunderstanding the tooling you speak of

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Re: Mill cylinder head/seat work without pilot

Post by Valve seat 1 » Wed Jan 22, 2020 11:50 pm

tt911er wrote:
Mon Dec 30, 2019 7:08 am
Hello all,

Firstly I'm pleased all the replies and comments and hopefully more of them coming.
If the idea cannot stand the criticism then it's not good enough or reasonable. Simple as that.

1. challenge is to get the guide straight up with x/y in place.
- if that is not possible to learn to do in a reasonable time by sweep dialing the guide hole then it will be very time consuming specially on a multi valve heads and makes no sense. If the guide hole is not round enough then that need to be fixed first with or without pilot I believe. If the needed guide work can be done on a same machine the position is there.

If the positioning can be done in a reasonable time then the idea was rely on the spindle mass and accuracy without any other movable parts.
Does this give the hoped results with quality vs. time. I don't know. That is the reason why I like to hear the comments.

Like I mentioned earlier I probably ending up using pilots and ball head but just wanted this forum to roast this idea.

And if we could leave the head fixture out of this. It has to be solid.

Happy New Year!
I do it quickly I make aluminum sleeves that are a slip fit in a R8 taper hard end mill holder the OD is 1-1/4 the I’d bore is a slip fit to whatever the top of the pilot I’m using mine are .375 I’m talking.0005 clearance ... with the pilot in the guide and the sleeve In the spindle I pull down on the sleeve towards the pilot and tweek my tilting fixture and the machine handles Until the sleeve slide on the pilot . If it’s not line up,the sleeve jams up . This gives a better feel then using the Machines quill.When it goes smooth On the pilot I’m straight up to the spindle. I pull the pilot out and cut with a rigid tool.

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Re: Mill cylinder head/seat work without pilot

Post by SchmidtMotorWorks » Thu Jan 23, 2020 12:56 am

Valve seat 1 wrote:
Wed Jan 22, 2020 11:03 pm
There are many different shaped inserts some with a radius in the bowl ect... However using a ball to single point or penciling the shape always leaves a cusp from the step over . Maybe I’m misunderstanding the tooling you speak of
Take a 0.125 ball-cutter at 0.005 step-over leaves a 0.00005 cusp height.

This type of machining is ordinary for mold-making today for about 10 years now, it has made mold polishing a thing of the past for anything except diamond compound polishing.

https://www.mmsonline.com/videos/hard-m ... -machining
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Re: Mill cylinder head/seat work without pilot

Post by Valve seat 1 » Thu Jan 23, 2020 1:06 am

I see ! I stand corrected. Thanks for the info.

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Re: Mill cylinder head/seat work without pilot

Post by modok » Thu Jan 23, 2020 3:45 am

So, uh.... how much would we have to charge per seat to make the payments on that mold carving machine? :shock:

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Re: Mill cylinder head/seat work without pilot

Post by jcisworthy » Mon Jan 27, 2020 9:20 pm

Valve seat 1 wrote:
Fri Jan 17, 2020 8:56 pm
The best way and simplest way to machine seats on a vertical mill or Bridgeport is bolt/ weld some square bar stock together a rectangle box shape 2” will do.
And bolt them to your rotary table standing the table straight up on one end of the table and then bolt a piece of round bar to the other side. Which will go in a pillar block radial bearing . A good sized one. 1-1/4 dia So you got two bars running parallel to the x axis. Skim cut the bars to the machine. Now you have a flat surface to put the head on. You can locate on the deck or valve cover surfaces or bolt a plate to it with slots and bolt it on the intake or exhaust surfaces . The sky’s the limit here.
You can Spin the rotary table to get the guides straight up
In one direction. The other direction is usually straight to up and on plane to table . If not . A simple machinist jack will do to tweak the head. To locate the guide straight to the spindle use bar stock/ pins / ground rod or drill blanks
Or just turn your own to various guide sizes. Could be Aluminum.Now take a block of metal drill and team various holes of different guide bores . Lay the block on the table of machine find a tight fitting rod. push it thru the guide with the head loose and when it goes in the reamed block lock the head down. Your straight up. Now you can indicate the the pin or the guide. Ready for rigid machining. No pilot to flex or two piece tool that’s a weak link.
And cost a 1000 dollars. I buy the cutter tip holders only and inserts
And machine the slots to hold it in 1-1/4 round stock with a hard end-mill holder a few set screws to lock it.
No need to spend thousands to make a mill into a valve seat machine. This is the job shop machinist approach. And it can be done without the bar fixture if you don’t do
A lot of heads.just a different set up. Same principle.
I have been using a rollover fixture on my mill for the past five years and your way sounds totally opposite from best and simple to me.

I have a new version coming out in a week or so with which you can level off any head with two wrenches! Canted heads, no problem, no adapters. Deck blocks with it also. It will be usable on a table 39 inches or longer. No that's the best and most simple for a mill.
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Re: Mill cylinder head/seat work without pilot

Post by Valve seat 1 » Mon Jan 27, 2020 9:29 pm

It’s not a roll over fixture. So your assumptions are wrong. If you read it all you will see I say I can bolt plate across it and hold on the intake or exhaust sides. The bars can take a vise and or fixture for other jobs non head related. So it’s multi functional. And all the materials and such is store bought

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Re: Mill cylinder head/seat work without pilot

Post by modok » Mon Jan 27, 2020 9:53 pm

I get it, I mean.....you'd scoot the head towards the rotary table, so it'd be more of a tripod. Could be better than many setups I see.
the trouble IMO with "most rollover" fixtures is they are only ONE length.
You make it LONG enough to do a six cylinder head, then mount a little 1/2/3 cyl head in the middle.....it's all flexy.
Which of course has lead most VGS machines to be built so you have two stands that can be spaced them wider or closer at will.....

I could also argue that any fixture wider apart than the saddle also loses rigidity, but that's almost a separate subject.

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Re: Mill cylinder head/seat work without pilot

Post by Valve seat 1 » Mon Jan 27, 2020 10:03 pm

When I bolt the head thru the bolt holes into a threaded bar across the bottom It doesn’t flex the head strengthens it. The head would have to bend. The only flex possible is the bar ends and at 2” dia 4 inches past the head on each side. Not going to happen. However if it did flex a simple machinist jack in the middle and down on the table would stop that. You didn’t explain your fixture. . But if you have to take it off and on for other jobs like the aluminum titling ones some dudes selling on you tube for a few thousand
It’s not for me

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Re: Mill cylinder head/seat work without pilot

Post by Dave Koehler » Tue Jan 28, 2020 7:31 am

The time has come to say
This thread is worthless without more photos.
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Re: Mill cylinder head/seat work without pilot

Post by jcisworthy » Tue Jan 28, 2020 8:45 am

Valve seat 1 wrote:
Mon Jan 27, 2020 9:29 pm
It’s not a roll over fixture. So your assumptions are wrong. If you read it all you will see I say I can bolt plate across it and hold on the intake or exhaust sides. The bars can take a vise and or fixture for other jobs non head related. So it’s multi functional. And all the materials and such is store bought
I understood it was not a rollover fixture and I also understand that what you are talking about in my book is far from best easiest on a mill.

If it works for you and you want to figure out more widgets need for each different head, that is fine, I'm just saying its not for me.
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Re: Mill cylinder head/seat work without pilot

Post by Howard Healy » Tue Feb 11, 2020 11:05 pm

It's funny no one had mentioned grinding the seats. I was a professional engine builder for over 20 years. I ground my seats with Sioux stones for most of it. I would then hand lap every valve after. I was able to run a VGS-20 for a short time while helping out a buddy who still builds high end engines. I very seldom got a seat concentric enough to lap in using the cutters. I would have to kiss the 45 with a stone to have it seal. If it was a re-freshen job, I could grind the seats within half an hour while keeping all the seat heights within .002. I now own and operate CNC equipment. I would not even consider a valve job on the CNC machine. I would pull the grinder out and get er done.
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Re: Mill cylinder head/seat work without pilot

Post by modok » Wed Feb 12, 2020 3:46 am

Same here. Home garage I have a good collection of seat grinding stuff, air driver, 8 holders, three dressers.
But there is also a need to cut seat pockets, and cut fresh new seats to shape.......

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Re: Mill cylinder head/seat work without pilot

Post by PmGRacer » Wed Feb 12, 2020 9:57 am

Here is a few pics of how I indicated each guide on my Bridgeport. Larry Meaux was where I found the process for doing the seats on a BP. The “puck” as I call it was turned from 4142 Pre Heat steel then ground top/bottom/od. I sent the puck to a jig grinder with my pilot and had the pilot bore ground for a snug slip fit on the pilot. The pilot bore was made concentric to the od of the puck.

I was able to indicate the guide in easily both in perpendicularity and concentricity fairly quickly. Every guide had to be indicated as they all were slightly off to each other. To me it made more sense to indicate a “plane” perp to the guide axis.
https://pmgiannosa.smugmug.com/Fixture ... /i-3wPw9RV

https://pmgiannosa.smugmug.com/Fixtures ... /i-gRhz5mk

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