Harder than my head !!!! iron buttplate drilling

[mountainman70]

Hello all; this has been a wonderment to me for several years,but more this morning as I was trying to drill iron Tenn style buttplate casting for the holes. Yep-got halfway into the top ext 1/8 new bit,lubed with atf.Did fine---then   3 new dulled bits later here I am. What goes on with these castings? Is the metal getting work hardened before I am thru playing now? Thanks a bunch,Dave

[Jim Kibler]

Thin steel castings can tend to be hard.  This is highly dependent on the alloy poured and the foundries ability to control chemistry.  An example...  I've used one foundry for steel buttplates, supposedly 8620, and they were quite hard.  These took long annealing cycles to soften.  I currently use another foundry for the same parts with the same alloy specified and they machine very well. 

In a foundry, chemistry control is largely dependent on scrap (returns) chemistry segregation.  It's also dependent on melt practice as well.  Many of the foundries used in the muzzleloading business are more than a little behind the times for sure.

[Scota4570]

Sounds like it is.  Try putting the butplate in a charcoal fire, like the BBQ.  Get it red hot then bury it in the ashes.  Come back in a day and extract your soft part.  Next try, run the drill  press slow, use cutting oil and a new or freshly sharpened bit.   

[smart dog]

Hi,
I have come to hate steel castings.  In every one over the last year I encountered the same problem you did.  I always anneal each casting at about 1550 degrees for 30 minutes and let cool in the oven, which takes several hours.  It is a pain in the neck.

dave

[Hungry Horse]

Some of modern steel castings are made from steel that are nearly impossible to soften enough to drill them. I had a small Hawken breechplug that couldn't be anealed with anything I had in the shop. Acetylene torch, blacksmiths forge, nothing worked. Getting it red hot and burying it in warm ashes for a day did nothing. I threw it away.

  Hungry Horse

[45-110]

you smiths that are located around bigger cities with tool suppliers can pick up a few carbide drill bits. the advantages of having a few on hand are many. they don't flex and out last hss many times over.  i seldom even reach for a hss drill anymore if i have a carbide one in the needed size. i run mine in the bridge port mill.
best kw

[Scota4570]

A carbide drill gets you a hole.  Yes, that will probably work, sort of.

Now the hole needs to be chamfered to fit the screw.  I do that with half reamers that I make from heat treated drill rod, to fit the particular  screw.  They will not cut a glass hard casting. 

It might be worthwhile to test the casting with a file before you get too deep into it.  If the file skates across the surface that is a red flag.  I have had several unusable casings shipped to me lately.  It is very frustrating, is there no quality control?  I would return a glass hard, or otherwise defective, casting for refund. 

Building rifles is challenging enough without fighting junky parts.

[oldtravler61]

   Scota your dead on....! Oldtravler

[45-110]

scota4570
they make/sell a carbide tipped 82 deg counters sinks also. easy fix again

[moleeyes36]

I don't do many iron mounted guns and I guess I've been lucky with the ones I've done.  But even given that carbide drills and counter sinks can take care of screw holes, even a wax casting is going to need file work to clean it up to use.  What do you use for that job if the casting is so hard that a file skates across the surface as Scota4570 mentioned?

Mole Eyes

[Mark Elliott]

I have used a lot of iron mounts, but was never aware of this problem with castings..   I make all my mounts from 1018 or wrought iron.   Sounds like making them from scratch might be cost effective time wise. 

[SingleMalt]

I just encountered this with a trigger plate from TOW.  I actually broke a cobalt bit and dulled a few HSS #21 bits.

[Scota4570]

I have used a lot of iron mounts, but was never aware of this problem with castings..   I make all my mounts from 1018 or wrought iron.   Sounds like making them from scratch might be cost effective time wise.

I'm going that way more and more often.  IF I mess up it is on me and I learned something.  IF somebody sends me junk then I get upset, loose time and money.   I'd rather do it myself and get it done right. 

On a curved surface a countersink is not the answer, at least to me.  IT makes an ugly oblong recess that does not fit the screw head all they way around.  When you dress downt he screw head you get a knife edge on the screw.  I don't care for that. 

IF you make countersink with a major diameter that equals the largest diameter of the  intended screw head it will fit neatly all the way around.  Then use a dome head screw.  If you dress it down you get a perfect fit and no knife edge.

No matter what all these parts are going to need to be filed flush with the wood.  IF it can not filed it is useless.  Send it back for a full refund and demand shipping costs.   

[David Price]

The last steel but plate that I used was a .......... to engrave.  That is the only one that i ever received that was like that.  The next time I get one I will send it back.

David Price

[Goo]

3 new dulled bits later here I am. What goes on with these castings? Is the metal getting work hardened before I am thru playing

You didn't say what type of drills you are using high speed steel? or those bright yellow ones?  The Hdw stores are so fond of selling nowadays

[mountainman70]

Cobalt and titanium bits. Been good enough before,just not now. I wonder if there is anyone in my area using laser to drill holes?
Be dang less hassle. I did heat the xxxx outa the plate,let it cool in the vise,and managed to get #6 screw holes in it. Man,I am glad to know you guys have had similar experiences. Thanks for all the replies. I like Mark Elliots ,I have never had trouble drilling hand forged parts,other than obtaining them. Thanks again guys. Dave

[Goo]

Cobalt and titanium bits.

Believe it or not I have had the best results drilling holes in ferrous metal like cast steel using plain old style high speed steel bits, as in the regular black oxide finish ones.     I use coolant or lube watch my pressure and slow the speed down.   I do have problems now and then but those gold colored bits work best on aluminum for me.   Sometimes the way the bits are sharpened and the tips are cut makes a big difference as well.   There might be a saw and tool sharpening place in your county ask them they can show you all the different ways to put the angles on the tips which get the best results. Good luck!

[Goo]

Here is some info on drill geometry  http://www.newmantools.com/machines/drillpoint.html       

[Eric Krewson]

It is good to hear that I am not alone in getting steel parts cast from ball bearings or something similar.

It took me half a day to grind off the casting sprue on my fowler butplate with an angle grinder, it was that hard.

The trigger guard I got at the same time was made from the same stuff. I broke two bits drilling the front lug hole, one on each side. The bad thing was I had a temporary phillips screw holding the trigger plate in and couldn't get the trigger guard off to replace the screw with the broken bits deep into the wood pinning the guard into place. My stock was still a plank at this point and I shaped the lock panel and wrist around the stuck trigger guard with a small file and sandpaper, very labor intensive. 

Later in the build a member here suggested I try to drill out the broken bits with a carbide tipped 1/16" bit by putting only the weight of the drill in the hole and going slowly. After about 30 minutes I saw metal dust coming out of the hole and "POP" I drilled through. I got the trigger guard off and replaced that dang phillips head screw that was haunting me.

[Bob Roller]

A carbide drill gets you a hole.  Yes, that will probably work, sort of.

Now the hole needs to be chamfered to fit the screw.  I do that with half reamers that I make from heat treated drill rod, to fit the particular  screw.  They will not cut a glass hard casting. 

It might be worthwhile to test the casting with a file before you get too deep into it.  If the file skates across the surface that is a red flag.  I have had several unusable casings shipped to me lately.  It is very frustrating, is there no quality control?  I would return a glass hard, or otherwise defective, casting for refund. 

Building rifles is challenging enough without fighting junky parts.

Cast steel parts for muzzle loaders started appearing about 1962 and quality control was non existent.
Hard as glass parts were common and apparently still are. I recently installed a J&S style trigger guard
on a set of my triggers and had to anneal it so it could be bent slightly. It broke later and I installed
another one that had to be annealed and so far so good---maybe.
I certainly remember lock plates for the Shoults lock breaking like glass** and frizzens that defied all
efforts of drilling and was told that sometimes ceramic inclusions occurred in investment cast parts
and no amount of annealing will get rid of them.
L.C.Rice told me the reputation of L&R lock Co. was devastated by the indifference of foundries to
requests for quality control and specific alloys for certain parts.He was told that "We do production,NOT
quality control". It's a roll of the dice even today to buy such parts as are available for our hobby/work
activities and the sellers like L&R and Chambers and TOW,Log Cabin and others will tell you this.
THEY catch the flak and static generated by foundries who supply them.THEY make the refunds or
replace junk parts they HOPED were OK and kill what profit they made to begin with. These are
the reasons I never went into selling bits and pieces made by others and used my shop skills to
fabricate as much as possible the locks and triggers I made. Also did a lot of automotive work
such as transmission bearings and ONE OFF requests for single items. The last one was for a
water pump shaft for a Duesenberg. Finding a shop that will do one of a kind work but the work
is there if you look for it.

Bob Roller

[Turtle]

 The hardest but plate I ever drilled was, amazingly to me. a sand cast german silver one. It was also a pup to file. I was unsure how to  aniele that stuff. other wax cast ones were fine. I won't do one of those again.

[Jim Kibler]

It's easy to be critical of investment casting and might satisfy the urge to promote doing things by forging etc, but fact of the matter is all of us in this depend heavily on the foundries.  Real problem lies in their processes and control.  I come from a foundry background and understand how important chemistry control is and the potential pitfalls.  It's not rocket science but simple practices need to be consitently followed.

[Bob Roller]

It's easy to be critical of investment casting and might satisfy the urge to promote doing things by forging etc, but fact of the matter is all of us in this depend heavily on the foundries.  Real problem lies in their processes and control.  I come from a foundry background and understand how important chemistry control is and the potential pitfalls.  It's not rocket science but simple practices need to be consitently followed.

Very true but in my case,I would NOT put all my eggs in one basket and that
led me to the automotive,one of a kind custom work.The price of bearing grade
bronze favored the idea and did for several years and an ad in Hemmings Motor News
did no harm either.That and the German market for my locks kept my wife from having to
go out to work when both boys were quite young.Also made quantity runs of bell housing
bushings for old GM,Packard and other long kaput transmissions.One rebuilder of industrial
transmissions was going to give me a big job but the maker of that transmission threatened to
cancel his franchise so that evaporated.That one would have been like finding money on the sidewalk.
The price of bearing grade bronze finally went up to the point where it was no longer practical to
continue making bearings so I started helping an old friend with his European car repair shop.
No real schedule and it made me appreciate American cars. Captive market Eurocar parts were
the determining factor there.
Would it be possible to set up a foundry dedicated only to the materials used by makers
of muzzle loaders and single shot rifles and could it support itself in today's economy?
Does anyone have any idea as to the total of these castings sold in a year?

Bob Roller

[P.W.Berkuta]

Gee -- I have run into this problem TWICE in 40+ years and I used a LOT of cast steel parts both sand cast and investment cast. My one time was with a Siler tumbler and the other was with a Siler lock plate. Both had "hard spots" that the HSS drill bit did not cut. I used a carbide drill bit to cut through the hard spot. I think these hard spots are from silica in the steel during the casting. This comes from the steel being processed for the pour - bad quality control of the melted steel used.

Sometimes the drill bit if run at high rpm's and without lube will spot harden the steel (depending on impurities in the mix) at the drill point causing hard spots. One must pay attention to speeds & feeds to prevent this. You also need to start with a sharp drill bit because a dull one will generate a LOT of excess heat at the drill bit point and cutting lips.

[jerrywh]

 I have had this problem a lot of times. Heat that portion red hot and let it cool slowly,  the when you drill it use a lot of pressure on the drill and don't let up.  The casting will work harden when you don;t use enough pressure.  The only other way is to use a carbide drill. It might help to drill a small hole first.