Author Topic: First engine, first goof  (Read 4184 times)

Offline plataman

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First engine, first goof
« on: December 17, 2016, 02:57:32 AM »
Well as newbie to engine building I was just waiting for my first disaster and here it is... Broke a 3/32 drill bit off in my brass wobbler. this creation is of my own design and started out life about 15 years ago. The plan was to build one for my inspiration, my Dad, and one for me. Well Dad passed away and everything went in the drawer until last week when I decided to build out one of the engines. All was going well until a drill broke off effectively scrapping the engine base. LESSONS LEARNED; here is what I believe to be the cause. All drills are touched up on my Drill Doctor 500 with good results. This 3/32 drill failed about .250 into the cut. All was going well then even though drilling brass things stopped as if I hit a steel screw or something, a second later the drill broke. Inspecting the larger drills showed a good grind profile from the Drill Doctor but who looks at those tiny bits? Well I finally looked at the two sizes on each side of the broken drill with a strong magnifier and found the tip relief angle to be way wrong; negative relief! It's a wonder it cut at all. On smaller bits I need to 1) be sure to position the bit precisely in the grinder collet and 2) adjust for an additional 10 degrees relief. Starting at about 3/16 the relief looked good, but beware on the smaller drills. Now back to the shop to remake the part. Terry

Offline ///

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Re: First engine, first goof
« Reply #1 on: December 17, 2016, 03:24:11 AM »
Hi Terry, sorry to hear about the snapped drill, I wonder if there is an acid/alkali that would eat the drill but leave the brass unscathed?
Or perhaps a makeshift EDM?
Seems a shame to scrap all that time and effort.
Simon

"The reality is that without cheap imported machines, I would be spending my time doing something less creative and less enjoyable" - Captain Jerry

Offline plataman

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Re: First engine, first goof
« Reply #2 on: December 17, 2016, 03:49:10 AM »
Thanks Simon, The HSS drill broken in brass does complicate matters. Fortunately I do have an unfinished column from the second engine for Dad, which will not be finished. Sooooo will finish that one for my engine. Need to share a great success on this job; the cylinder. I wanted a decorative look rather than just a square block. Could have done a file job or belt sander but used the lathe as a shaper to make fins. Turned a round nose tool sideways in the tool holder and used the spindle indexing holes on the Atlas lathe to set locations. Then moved the carriage to cut the fins. Turned out nice. Good to have a success to dilute the goof. Terry

Offline JR72

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Re: First engine, first goof
« Reply #3 on: December 17, 2016, 09:53:57 AM »
Hi
I broke a 7ba tap in a bronze cylinder, of course it happened to be the last of 16 holes. I was absolutely devastated after spending so much time on the cylinder and the thought of obtaining a replacement and start all over again made me feel gutted and ready to give up. But I found a solution via google. The exact details I can probably help you with if you are stuck but basically you mix Alum Crystals (obtainable quite cheaply from chemists} with water place in a Pyrex dish and place the whole thing into a saucepan of boiling water and let it simmer, it takes quite a while but it definitely works and the bronze was undamaged. If you would like more details with photos I will see what I can find.
Good luck
John 

Offline sshire

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Re: First engine, first goof
« Reply #4 on: December 17, 2016, 02:16:49 PM »
Stuff happens and we've all had it happen to us at some point. Since no one is paying us to do this stuff, the main loss is time and a bit of metal. I know the feeling of working on a part for a long time and having something screw it up. My procedure is to stop. Turn out the lights. Take a breath and think about what caused the problems. The remake takes much less time than the original since you've had practice on the first part. Push on.
Re: the alum fix. It will not work with HSS taps. DAMHIK.
Best,
Stan

Offline ShopShoe

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Re: First engine, first goof
« Reply #5 on: December 17, 2016, 02:40:07 PM »
plataman,

I like the look of the fluting you created on the cylinder. Thank you for showing some good outside-the-box thinking in coming up with a way to do that.

You will get past the broken bit. We've all been there. I bought a Drill Doctor two years ago and I am also only moderately happy with the work that it does. All my efforts at drill sharpening with lots of different devices and lots of different techniques ends up as "Sometimes it works well, Sometimes it doesn't work" (This includes by hand with just a grinder). Count it up to experience and tell your friends it was Murphy, the Shop Gnomes, the Alignment of the Planets, your Mother in Law, and Not Holding Your Mouth Right.

Best of Luck on the rest of the project.

ShopShoe

Offline plataman

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Re: First engine, first goof
« Reply #6 on: December 17, 2016, 02:52:18 PM »
Thanks to all for the kind words. I have never heard about the alum solution but may try it just to see if it works. Interesting. Your suggestion of turning off the light is a good one as everything else I touched that day turned out not so good. A bit of reflection on the drill point geometry and a cold beer did seen to help my spirits. Inspecting many of my smaller than 1/8" drill bits with a strong magnifier revealed a zero or negative rake on the drill point so its back to the Drill Doctor 500 for an adjustment and resharp. The next day I came up with the cool fin idea for the cylinder using the lathe carriage as a shaper. Everyone have a great holiday! Terry.

Santa, please send an Aloris tool post and a rotary table.

Offline plataman

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Re: First engine, first goof
« Reply #7 on: December 17, 2016, 03:01:30 PM »
Thanks Shopshoe.

(I have had shoes torn up by chips when working as a milling machine operator as a summer job way back when, amused by your Shopshoe). On the Drill Doctor 500; Seems to do an OK job but technique is oh so important. The orientation of the smaller bits is difficult and super important. The manual rotation and rocking action during the sharpening process needs to be uniform, same pressure on both flutes and keep the collet cam riding on the pin at all times as the plastic parts are far from firm and precice. I have found that the smaller bits, 1/8 and below, need a  bit of extra rake on my machine. Always inspect the point with a magnifier when finished grinding. We need to THINK about what we are doing and save the beer for later. Merry Christmas! Terry

Offline PJW

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Re: First engine, first goof
« Reply #8 on: December 17, 2016, 08:15:07 PM »
I broke a tap in a aluminium manifold, i had drilled & tapped a dozen or more holes & I was sick at the thought of doing all that work again. I put in a strong solution of Alum & the tap just went black & crumbled away after an overnight soak. I got the tip from one of our members, cant remember who :shrug: but thanks again!
Old Guys Rule the Dark Side of the Shed!

Offline PStechPaul

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Re: First engine, first goof
« Reply #9 on: December 18, 2016, 09:37:20 AM »
I have removed broken drills and taps in soft materials by using sharp tweezers or a needle nose pliers pushed into the flutes, and using small vise-grips to exert force close to the broken piece. Sometimes I also used lubrication and it also helps to use a prick punch or similar tool with a small hammer to loosen it up and back it out. If the threads get too buggered up you could drill and tap one size larger, or use a helicoil. Another possibility is to drill a hole that is a force fit for a rod of the same material, perhaps heating the part and freezing the rod, and maybe using some sort of adhesive. Then you can re-do the drill-and-tap operation.

Can you take a picture of the goof?

Offline Ian S C

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Re: First engine, first goof
« Reply #10 on: December 18, 2016, 02:41:16 PM »
the Alum solution works by electrolytic means. Ian S C

Offline plataman

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Re: First engine, first goof
« Reply #11 on: December 18, 2016, 06:40:18 PM »
Yes, I can take photos of the part. I would like to try the Alum process as this is a small drill; 3/32 inches or .093 in diameter. likely too small for the needle nose idea. Too cold to venture out to the shop today, probably be Tuesday before things warm up enough where I don't spend a small fortune heating the place. Given this is a smaller part I started a new one to continue the project. If you read my original post I started 2 of these engines many years ago and now decided to finish out one only. So I have most of the roughed out parts from the other engine still in the drawer.   

Offline Alan Haisley

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Re: First engine, first goof
« Reply #12 on: December 18, 2016, 08:02:49 PM »
Be sure to use a glass or ceramic sauce pan. You only want the reaction to be between the part and the drill.  :old:


Alan

 

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