Lightened Gudgeon Pin

[Stoneman]

Nice job on the MQL mister, much less mess than flood coolant.

Couple thoughts on this. As you're finding out, carbide drills don't like opening up existing holes, they much prefer drilling from solid. All carbide drills are not created equal and there are tools designed for high hardness steels. OSG Tap & Die has tools that will drill into the 60's HRC, and I've seen demos of their tools drilling and tapping files. Many other companies have similar tools, but I'm not familiar with distribution in Australia. Word of warning, as the technology increases, so does the price.

Maybe consider trying carbide reamers. They are designed to open existing holes and can take fairly large depth of cuts. Might take a couple of different diameters to arrive at your final dimension. Or, if your finished dimension matches that of an end mill, feeding a four flute end mill with a large corner radius would cut that pin all day.

Not trying to complicate your life here, just throwing out some ideas that might work. Good luck!

Thanks for that, they are great suggestions,
I have adjustable reamers but they would crap out with hardened steel, and I use them to only bore out the stock carbs to 14.6mm than reseat the slide base
Your spot on, they don’t like opening up holes, no drill bits do really
I will look into your suggestion though
First drill bit was $168 and got 7 holes
2nd two $68 and got 3 holes each, but that makes the pins rediculous price I feel

What we suspect is already mentioned and that’s that they loose there coating and just don’t perform and especially that I’m boring out holes

I’m not giving in easy, I will go speak to an experienced machinist and see if I can pinch some of his expert knowledge

How ever I manage to do it must be feasible to do for a reasonable price.

 

[HeadSmess]

when you watch one of these sinking 100mm into steel without pecking, a few hundred times... you give up on drill bits.

the drill bit is the wrong tool for it.

of course, youre going to have to spit out at least a 100 of these to make them worthwhile. in a day.

thats what these people saying" you should make these and sell them" dont realise...it costs money to make them. its alright spending half an hour making one for yourself, but they should take about ten seconds for a factory. china skips that step and just uses driller rod...its already got the hole in it from the steel mill.

yes, you can get boring bars that small, but i dont think single point is the way. reamers are only good for 0.15mm or less. they arent intended for opening up holes, just finishing them to accurate sizes. and still expensive. the above pictured Tdrill is basically a double point boring bar. lots of sizes available.

the hafco metalmaster lathes are not suited for carbide tooling other than roughing tools. way too much slop in the ways. the tailstocks arent aligned properly in either axis (have you ever taken it off and had a look at the slideways in the tailstocks? mine touches in three spots...less than half a cm^2 in total)

for this job, you shouldnt even be using the tailstock. use the toolpost and get it square in both axes, then use power feed. carbide needs consistent feeds.

solid carbide drills require spot on accuracy, they have no flex, no give. thats why almost noone uses them. too expensive. not worth it.

just get yourself a masonry drill bit and a greenwheel on the grinder (silicon carbide stone). total cost? about $20.

we always used masonry drills for this sort of job in production work. the steel shank lets them wriggle. coring out castings with far more eccentricity than even chinese gudgeon pins have. with hard spots and all.

and yeah, theres a hell of a lot of different types of carbide out there. some carbides can machine other carbides. some carbides go dull simply rubbing on cast iron. most metal machining carbides are actually tantalum, titanium, and tellerium. not tungsten at all.

last option...stellite. better than HSS, but more forgiving than carbide. good luck finding any anywhere other than an old guys garage sale though...

 

[Stoneman]

when you watch one of these sinking 100mm into steel without pecking, a few hundred times... you give up on drill bits.

the drill bit is the wrong tool for it.

of course, youre going to have to spit out at least a 100 of these to make them worthwhile. in a day.

thats what these people saying" you should make these and sell them" dont realise...it costs money to make them. its alright spending half an hour making one for yourself, but they should take about ten seconds for a factory. china skips that step and just uses driller rod...its already got the hole in it from the steel mill.

yes, you can get boring bars that small, but i dont think single point is the way. reamers are only good for 0.15mm or less. they arent intended for opening up holes, just finishing them to accurate sizes. and still expensive. the above pictured Tdrill is basically a double point boring bar. lots of sizes available.

the hafco metalmaster lathes are not suited for carbide tooling other than roughing tools. way too much slop in the ways. the tailstocks arent aligned properly in either axis (have you ever taken it off and had a look at the slideways in the tailstocks? mine touches in three spots...less than half a cm^2 in total)

for this job, you shouldnt even be using the tailstock. use the toolpost and get it square in both axes, then use power feed. carbide needs consistent feeds.

solid carbide drills require spot on accuracy, they have no flex, no give. thats why almost noone uses them. too expensive. not worth it.

just get yourself a masonry drill bit and a greenwheel on the grinder (silicon carbide stone). total cost? about $20.

we always used masonry drills for this sort of job in production work. the steel shank lets them wriggle. coring out castings with far more eccentricity than even chinese gudgeon pins have. with hard spots and all.

and yeah, theres a hell of a lot of different types of carbide out there. some carbides can machine other carbides. some carbides go dull simply rubbing on cast iron. most metal machining carbides are actually tantalum, titanium, and tellerium. not tungsten at all.

last option...stellite. better than HSS, but more forgiving than carbide. good luck finding any anywhere other than an old guys garage sale though...

Your spot on and thank you very much for your input.

At the moment I have got a decent drill bit sharpener and will see what I get from them until they are useless
It’s called a Drill doctor and so far seems to do a very good job being able to adjust the cutting angles but yet to test them cutting.

The mansory bit has me intrigued though, how do I go about sharpening them for metal?

Thanks again

Just a side note there is different size/weight pins
I have found 3 that have different weights

 

[HeadSmess]

i said how. with a greenstone on a grinder. surely if you have a lathe you have a bench grinder as well? how do you deal with HSS otherwise? dont tell me your an insert man! yuk... i use inserts but only for special jobs. otherwise i use HSS, stellite, and brazed carbide tools.

just waddle down to (i assume its hare and forbes) and get a greenstone, aka silicon carbide wheel.

most hardwares should stock them as well. not bunnings, as far as i am aware.

i refuse to use those drill dr things. they arent proper drill sharpeners at all. just grind them freehand. a real drill grinder costs about $1500 minimum. you could get an old second hand surface grinder for that sort of price, which would allow you to grind...just about anything, with the right attachments (like an indexing head, etc...). hell, if you found the right internal grinder attachment, and suitably sized stones, you could GRIND these hole out!

the only way to grind a drill properly is to practise and watch how they perform. you can always make a jig to mount on the grinder though, for real accuracy.

if you do a lot of grinding... get a diamond wheel intended for surface/tool grinders. the greenstone works, but theyre also messy. green dust going everywhere. and need dressing/truing on a regular basis. diamonds last virtually for ever...just do NOT grind steel or anything BUT carbide with them.

this old tony on youtube has a decent video explaining most of the reasoning behind sharpening a drill. as well as most other things related to machining. good old youtube.

 

[Stoneman]

I have never seen a masonry bit drill steel, the masonry bits I'm used to obviously need to be changed to cut steel so i guess you just sharpen it like a normal drill bit.

Actually the drill doctor does a very good job and is one of the higher end models but that dosent matter anyway and its been many years since ive done one by hand. Matter fact the drill sharpener would be close to that in US$. Im happy to move along with the times, I do enough work with my hands with stone so im quite happy to use carbide inserts unless i have no choice

The bit you posted has inserts and i dont think a man should be judged by his inserts haha , but yes i am learning how to sharpen HSS bits but i use the insets for the basic stuff

I will get some time tonight and google this grinder thing you speak of.

 

[HeadSmess]

dont get me wrong, i love and use inserts, and for some things they are vital...

but as they are damn expensive i prefer using HSS blanks, and sometimes you HAVE to! i cut gears with a plain bit of hss ground to a trapezium shape in a fly cutter rather than invest in a set of involute cutters. the maths is interesting


he really skips past the important bit.

Pitch Circle Diameter * pi / (360/X)= Y

X being the degrees of rotation per cut, Y being how far to lift (or lower) the tool per index movement.

if you only rotate 1 degree each cut, you get super accurate gears generated...way better than involute cutters achieve. just slow.

rotate 5 degrees each time and you get coarse faceted teeth, that work but are a bit noisy... quicker to make. obviously.

one day i might write up some code so i can do it on the CNC mill with a slitting saw.
tilt the 4th axis up and throw in a rotational move as it cuts and you can make helical gears. no fancy tools or software required. (other than the CNC machine!)

strangely enough...theres a company that supplies HSS inserts, because some jobs actually require its properties. you thought carbide inserts were expensive? the HSS ones have to be individually ground. not mass produced in an oven!

yep. just sharpen a masonary bit exactly like a steel bit.

they are better than solid carbide drills not only because the shank lets them wriggle, but they also have a "negative rake" top face, unlike HSS and solid carbide drills, with their positive rake.

positive rake really weakens the cutting edge. if you look closely at inserts you will see they are slightly rounded, and ground brazed tools will have a land or flat ground on the edge. it gives the cutting edge a lot more strength. it also means you need a lot more power to drive them and they tend to bend thin work.

and thats why the HSS inserts sometimes are necessary