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Resurfacing Aluminum Heads with a Rotary Broach...


Anyone out there have a van norman 530 or 570 rotary broach? I have been playing with aluminum...

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  #1  
Old 12-25-2010, 12:36 AM
Scotts439 Scotts439 is offline
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Default Resurfacing Aluminum Heads with a Rotary Broach...

Anyone out there have a van norman 530 or 570 rotary broach? I have been playing with aluminum heads on it trying to get that "perfect " like glass finish. I have the 2 speed model, and on the low low speed, it comes out almost perfect. Still getting a "little dragging of material", even tried silicone sprays, etc. Any ideas...? bigger cut, slower traverse speed, or slighter cut, faster traverse? I will typically take .003" per cut but I amgoing to experiment with deeper cuts. Any success with either the VN or the storm vulcan 85 on aluminum... thanks in advance.
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Old 12-25-2010, 09:03 PM
jwx3 jwx3 is offline
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Default Re: resurfacing aluminum heads with a rotary broach...

Have you tried pledge spray wax or something like dry slide
I converted my old broach to variable speed and that helped
But did not eliminate the problem
Now I use a single PCD poly crystalline diamond with excellent results
On a 16 inch cutter head and a single insert.
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Old 12-26-2010, 01:29 AM
wagspe208 wagspe208 is offline
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Default Re: Resurfacing Aluminum Heads with a Rotary Broach...

I a a Storm Vulcan. With a variable speed it gives prretty good finishes. It also has the replaceabvle carbide inserts in the broach. My applications don't require the super smooth ra finish, though.
Wags
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Old 12-26-2010, 09:39 AM
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Jeff in PA Jeff in PA is offline
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Default Re: Resurfacing Aluminum Heads with a Rotary Broach...

I haven't used a rotary broach but on a mill with carbide insert cutters, Tap Magic works good. Keeps the back cutting edge of the cutter from leaving drag marks.



http://www1.mscdirect.com/CGI/NNSRIT...MT4NO=99910213

Jeff
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Old 12-26-2010, 12:21 PM
Phil P Phil P is offline
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Default Re: Resurfacing Aluminum Heads with a Rotary Broach...

Hello

I have only known one machinist that could get a smooth cut on aluminum heads using a broach.

The broach was 24 inch in diameter and had 16 teeth. He had to sharpen the tools so they were all exactly the same. They had to be set with a positive rake. The when mounted in the broach he used a dial indicator to make sure the tool cutting depths was with in .0005 thousands of an inch. Use the higher speed. Use large amounts of oil 40-wt-engine oil or good cutting oil. The oil keeps the cutting tools clean of aluminum so you need to feed the oil in large amounts. My machinist used a pump and flowed oil continually while cutting. Cut depth is at the discretion of the machinist. .003 is a good place to start.

Smearing of the aluminum is the result of a dull tool and or negative rake. Miss aligned tools cause a groove for the tool that was low. Extensive “Galling” was the result of low volume of oil.

My machinist retired at 35 and don’t do heads anymore.

Phil P
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Old 12-26-2010, 10:06 PM
Dave Richards Dave Richards is offline
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Default Re: Resurfacing Aluminum Heads with a Rotary Broach...

Phil:
I do aluminum heads daily on a 858 Kwik-way grinder using a single point flycutter with either a small diameter round carbide insert or a tool that I made that uses 0 rake triangular carbide inserts that I lap by hand to give a rounded cutting edge but lots of clearence rake on the bottom. I don't think the positive rake is quite as important as the clearence. It runs at a pretty high speed, dry and I can get a very nice glassy finish at about .003" finish cut. If it starts to pick up a little metal, It's time to lap the tool again...mostly around the bottom and a little on the face. The alloy and hardness on auto heads varries alot and that effects the finish you get. Soft sand cast Mercedes or MBW are the worst. Most Chrysler products and Hondas are the hardest and easiest to get a good finish on. With the new multi layer rubber coated gaskets, finish is VERY important and most shops around here won't take the time to figure out how to produce a good finish. Keep experimenting, good luck. Dave Richards
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Old 12-27-2010, 09:12 AM
Scotts439 Scotts439 is offline
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Default Re: Resurfacing Aluminum Heads with a Rotary Broach...

Thanks Dave, are you able to use a pcd bit on the 858? Any luck with goodson grind-aid.
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Old 12-27-2010, 09:44 AM
Phil P Phil P is offline
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Default Re: Resurfacing Aluminum Heads with a Rotary Broach...

Dave

I never did aluminum heads. Only cast iron. I was repeating the instruction given to me by a retired machinist now 40 years old and catching a lot of fish. He developed this method using an old Van Norman machine with the multiple tools on a broach. He also at a latter date had a couple of other machines for these heads and he did indicate they were easy to use.

As you indicate the tool quality is the key. A dull tool is the most common cause of problems. The lack of clearance between the non cutting part of the tool and the cutting edge will also create a poor cut but this applies to just about any cutting tool and is the primary problem that happens when some one tries to sharpen a drill bit with out having received proper instruction.

Phil P
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Old 12-27-2010, 01:44 PM
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Default Re: Resurfacing Aluminum Heads with a Rotary Broach...

My search of Rotary Broach came up with tools for forming splines, and other similar shapes on the end of a part in a screw machine. What are you resurfacing in a head with such a tool?
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Old 12-27-2010, 02:21 PM
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Default Re: Resurfacing Aluminum Heads with a Rotary Broach...

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Originally Posted by John Newman, Jr. View Post
My search of Rotary Broach came up with tools for forming splines, and other similar shapes on the end of a part in a screw machine. What are you resurfacing in a head with such a tool?
I am interested to. The only broaches I have used were either for cutting key ways, splines and internal hex shaped holes. The rotary broaches I have used were used in a lathe for making internal hexes after the hole was drilled. I never had the occasion to use the rotary broach that cut internal splines.

http://www.slatertools.com/rotarybroaches.htm

Sounds to me from the description you are using a large face mill and calling it a rotary broach? A picture would be nice if you have one.

Richard W.
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Old 12-27-2010, 02:56 PM
Phil P Phil P is offline
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Default Re: Resurfacing Aluminum Heads with a Rotary Broach...

http://www.americanbroach.com/Broaching.html

http://www.dsbn.edu.on.ca/purchasing...p?item_id=7568

Last edited by Phil P; 12-27-2010 at 03:12 PM.
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Old 12-27-2010, 03:20 PM
Scotts439 Scotts439 is offline
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Default Re: Resurfacing Aluminum Heads with a Rotary Broach...

Anyone who is not an "automotive" or engine machinist would hear broach and think of keyways. Do a google search on the van norman 570 rotary broach. It is a resurfacing machine which is actually a big facing mill. multiple cutting bits on a big wheel which traverses a cylinder head that is fixtured to the machine. I guess they called it a broach because of the multiple cutter bits?
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Old 12-27-2010, 04:44 PM
pegasuspinto pegasuspinto is offline
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Default Re: Resurfacing Aluminum Heads with a Rotary Broach...

What kind of head is this? is it OverHead Cam? The perferred method there is to bake it straight and then clean it up with a special belt sander. Remember it;s the whole head that twists, not just the surface warping, and if there is a cam in it, the cam now is being forced to work around a corner....
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Old 12-27-2010, 05:36 PM
Richard W. Richard W. is offline
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Default Re: Resurfacing Aluminum Heads with a Rotary Broach...

So I was right it just a large face mill by another name.

Richard W.
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Old 12-27-2010, 06:21 PM
Phil P Phil P is offline
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Default Re: Resurfacing Aluminum Heads with a Rotary Broach...

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Originally Posted by Richard W. View Post
So I was right it just a large face mill by another name.

Richard W.
In accordance with the definition of “Broaching” it is named correctly.

Phil P
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Old 12-28-2010, 01:45 AM
Richard W. Richard W. is offline
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Default Re: Resurfacing Aluminum Heads with a Rotary Broach...

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Originally Posted by Phil P View Post
In accordance with the definition of “Broaching” it is named correctly.

Phil P
Not in my book. Broaches are usually pushed or pulled through a part. There may be some little know history behind this machine which has over time attached the name broach to it in some circles. But not to the general non automotive machine shops.

http://www.use-enco.com/CGI/INPDFF?P...MITEM=395-1650


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Richard W.
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Old 12-28-2010, 05:19 AM
Phil P Phil P is offline
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Default Re: Resurfacing Aluminum Heads with a Rotary Broach...

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Originally Posted by Richard W. View Post
Not in my book. Broaches are usually pushed or pulled through a part. There may be some little know history behind this machine which has over time attached the name broach to it in some circles. But not to the general non automotive machine shops.

http://www.use-enco.com/CGI/INPDFF?P...MITEM=395-1650


My view for what it worth.

Richard W.

Her is what the book says.




What is Broaching?

Broaching is a machining method in which a series of cutting teeth each remove a portion of stock as the cutting tool (broach) moves past or through the work piece. It combines both roughing and finishing in one operation and removes stock to precise tolerance faster than any other known metal cutting process. Because each tooth of the broach removes only a small amount of stock, a properly designed broach with good care will produce a large number of parts before requiring sharpening.

Note the “moves past” right after (broach).

That makes the major portion of the machine a “Broach” so the name Van Norman and other manufacturers use to differentiate between the grinding machines used for surfacing cast iron heads is correct terminology.


Phil P
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Old 12-28-2010, 02:39 PM
Richard W. Richard W. is offline
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Default Re: Resurfacing Aluminum Heads with a Rotary Broach...

Quote:
Originally Posted by Phil P View Post
Her is what the book says.

What is Broaching?

Broaching is a machining method in which a series of cutting teeth each remove a portion of stock as the cutting tool (broach) moves past or through the work piece. It combines both roughing and finishing in one operation and removes stock to precise tolerance faster than any other known metal cutting process. Because each tooth of the broach removes only a small amount of stock, a properly designed broach with good care will produce a large number of parts before requiring sharpening.

Note the “moves past” right after (broach).

That makes the major portion of the machine a “Broach” so the name Van Norman and other manufacturers use to differentiate between the grinding machines used for surfacing cast iron heads is correct terminology.


Phil P
The machine in question uses a rotary tool which finishes in one cut and a rough cut would require another previous pass. All the teeth are at the same height. Your definition states both rough and finish in one pass.

A broach has the teeth at multiple heights from cutting under size on one end to finish size at the other, so in one cut it both roughs and finishes. As stated by some else in a previous post the cutting tools are aligned with in .0005". The machine in question is a specialty machine with a face mill to do one purpose and that is to take a finish cut on premachined heads that have been warped. Why they call it a broach? I don't know.

Pictures of the "Tool Engineers Handbook" published by ASTME to follow when I get the scanner hooked up and running.

Richard W.
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Old 12-28-2010, 03:13 PM
Phil P Phil P is offline
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Default Re: Resurfacing Aluminum Heads with a Rotary Broach...

The cutting head in the Van Norman machine is a broach. The machinist setting the cutting tools to all the same position in order to get a finish cut when the previous method was not giving the desired result doesn’t change definition of “broach”.

Phil P
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Old 12-28-2010, 03:59 PM
Dan Brown Dan Brown is offline
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Default Re: Resurfacing Aluminum Heads with a Rotary Broach...

It never ceases to amaze me how far off track these posts get. I believe the original question had to do with surface finish.
Surface finish is a product of alot of things, Material type, Feed rate, Cutter type, Cutter material, Cutter profile, Depth of cut, Tool pressure, Part clamping, Coolant usage, Type of coolant, Machine rigidity, Tool holder type, these are just a few.
It seems to me that with all the cumulative years of machine experince, here on the stack, discussing any one of these would be far more productive than debating Broach or Mill. We all know what were talking about now lets help Scotts439 out.

Dan Brown
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