# ROUGHING END MILLS



## Dusty (Mar 21, 2019)

Hi list, last fall I tried to modify several off shore manufactured 3/8" T-nuts. So there went a new 1/2" cobalt end mill in the scrap bin. Yes all my fault because I didn't realize just how hard these off shore T-nuts were although I did have the speed up some. hmmm.....

Have never used a standard or fine roughing end mills before and I really don't want to screw up another end mill. 

What say you on my using a 'fine roughing end mill' to complete this task? 

Comments and suggestions welcome 

Bill


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## Dabbler (Mar 21, 2019)

If they are too hard for a cobalt end mill then it doesn't matter what the form factor is, it's too hard for almost anything unless you go carbide.  

Have you tried the file test to see roughly how hard they are?

If they are carburized, then they will chip most carbide end mills as well.


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## Dusty (Mar 21, 2019)

Dabbler said:


> If they are too hard for a cobalt end mill then it doesn't matter what the form factor is, it's too hard for almost anything unless you go carbide.
> 
> Have you tried the file test to see roughly how hard they are?
> 
> If they are carburized, then they will chip most carbide end mills as well.



Yes first thing I did was select 4 of the 16 T-nuts at random and check them with not one but two files. All things said milling the T-nuts appeared doable to me. Wish I had a huge shop with loads of floorspace and equipment like a surface grinder etc. 

One can only fit so much into a single car garage perhaps the boss will allow me to use our spare bedroom. Would you ask her! LOL

Bill


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## Tom Kitta (Mar 24, 2019)

Even some carbide EM will have issues and you exceed their recommended hardness use - i.e. most common carbide grades are for hardness up to around 45 or 40 etc. If someone hardened these T-nuts good they may be 50 - 60 HRC. 

"soft" carbide will still cut it but life of the EM will be shorter - there are carbide grades for hardened stuff....

Who don't you try to anneal these T nuts and harden them later on?


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## ducdon (Mar 24, 2019)

If their that hard I doubt you will mill them successfully. Why not start with some keystock and make a new set. Are you clamping that hard that you need them heat treated?


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## PeterT (Mar 24, 2019)

I had similar issue on some poorly made clones. They seemed like 4140-ish type materials but semi hardened. Did not like being milled & also did not like the threaded holes being chased with HSS tap. I have made some custom ones out of regular CRS unhardened & they have stood up quite well, although its a light duty application & not seeing perpetual tightening. Depending on your application you may want to chisel pop the last thread on underside to prevent the mounting bolt from protruding. Some have this some dont.

Te-Co makes nice ones if you end up buying
http://catalog.te-co.com/category/t-slot-nuts


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## Janger (Mar 24, 2019)

https://www.specialinterestmodelbooks.co.uk/?s=Harold+Hall&submit=Search

Harold Hall is a particularly clear author. His books on milling got me started. Worth buying. An early project is making t-nuts without a vise.


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## Janger (Mar 24, 2019)

WilliamG said:


> Yes first thing I did was select 4 of the 16 T-nuts at random and check them with not one but two files. All things said milling the T-nuts appeared doable to me. Wish I had a huge shop with loads of floorspace and equipment like a surface grinder etc.
> 
> One can only fit so much into a single car garage perhaps the boss will allow me to use our spare bedroom. Would you ask her! LOL
> 
> Bill



Garages are for tools not cars.


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## kylemp (Mar 24, 2019)

WilliamG said:


> Yes first thing I did was select 4 of the 16 T-nuts at random and check them with not one but two files. All things said milling the T-nuts appeared doable to me. Wish I had a huge shop with loads of floorspace and equipment like a surface grinder etc.
> 
> One can only fit so much into a single car garage perhaps the boss will allow me to use our spare bedroom. Would you ask her! LOL
> 
> Bill


You know.. The nice things about machines is you can move them in when she's not around and there is very little chance she can get them out later.. Better to beg for forgiveness..


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## Chicken lights (Mar 24, 2019)

kylemp said:


> You know.. The nice things about machines is you can move them in when she's not around and there is very little chance she can get them out later.. Better to beg for forgiveness..


When it comes to the wife....

And messing with her house....

You’re braver than I am...

Just saying


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## YYCHM (Mar 24, 2019)

When I was trying to figure out how to get a 600# lathe/mill combo into our basement my wife balked suddenly.

I quote..... "How am I going to get that thing out of the house when you're gone and I need to move out".

How's that for thinking ahead.. LOL.


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## trlvn (Mar 25, 2019)

YYCHobbyMachinist said:


> When I was trying to figure out how to get a 600# lathe/mill combo into our basement my wife balked suddenly.
> 
> I quote..... "How am I going to get that thing out of the house when you're gone and I need to move out".
> 
> How's that for thinking ahead.. LOL.


I keep telling her, call my friend Darrell.  He gets the tool that I 'stole' from all the other guys at the auction...yes he knows exactly what I'm talking about.  He gets the tool if he helps organize the sale!

Craig
It's a woodworking tool, a shoulder plane.  There was a row of them for sale but only one had the coveted skewed blade.  The auctioneer announced that if you won a bid, you could have the plane and as many of the following as you wanted at the same price.  Apparently no one other than me seemed to catch on.  When I bought the plane just before the skewed one (for cheap), and then took the skewed one for the same money, my buddies were gobsmacked!  Score!!


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## Tom Kitta (Mar 25, 2019)

Auctioneer did it on "choice". Say there were 10 items that were similar. Auctioneer lets you pick if you win - you can have any of the 10 or as many as you want including all 10.

This is all handy dandy except when as in your case one is better then the other 9 - then the bidding can go up high if people catch on. But that winner can just take the best one and no one else can take it at win price unless they don't notice the difference and are eaten. 

I had a situation with two welders - there were two interested parties - me and guy X buying on choice. Both welders were identical. Bidding went to $350 and I dropped out - he picked just one. I was asked to buy the send one for $350 and I refused - bidding re-commenced and I got it for $200. I was afraid the guy may beat me up with it. 

Lately auction stuff has sold for quite a lot in most consumer item categories - I saw a tiger torch from PA sold on action for $42 plus fees while literally I got the same one for $17 two days before at PA new - I think they still have them for $17 today. People just assume its "cheaper" b/c its auction - which frequently is not the case - not even close.


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## historicalarms (Mar 26, 2019)

It only takes one fool to screw up a marriage but two to screw up an auction.

    Well most of them anyways, my old neighbor took two horse's and a 40 pounder of whiskey to a horse auction one time...he came home with 32 horses and no whiskey...and ended up with no wife over it.


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## Tom O (Mar 26, 2019)

historicalarms said:


> It only takes one fool to screw up a marriage but two to screw up an auction.
> 
> Well most of them anyways, my old neighbor took two horse's and a 40 pounder of whiskey to a horse auction one time...he came home with 32 horses and no whiskey...and ended up with no wife over it.



Well you have to go with what works!


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