Making a tapered D bit

[tornitore45]

There is no need to case harden Drill Rod or Silver Steel since it has already ~1% carbon. Heat with what you have and quench in Oil or Water or Brine depending on the grade. (If you are inclined to be that sophisticated, otherwise water works or it may crack a large part.)
If you plan to cut steel, temper to a pale yellow and quench or set in the toaster/oven set to ~ 400 F for about 20 minutes, look out for SWMBO. If you cut only Aluminum tempering is optional.

Case hardening is not really an home shop option, at least in my shop.

 

[tornitore45]

A job well done Brian! I hope you protected the lathe way from the grit, rag not shown in the photo.

 

[Niceonetidy]

I use this method for making plug cock taps and valves. Cut the taper on the D bit, and then the plug while the cross slide is at the same setting. Always works.

Cheers

Colin

 

[Brian Rupnow]

tornitore45--My lathe thanks you. I haven't used it much since I ground the tapered D bit, and it was pig dirty. I just spent an hour doing clean up duty and re-oiling the ways and all the rotating and sliding surfaces. I don't clean my lathe that often, as nobody sees or uses it except for me, but it was in really nasty condition. I generally just use the shop vac to pick up all the chips and crud, but it needed a lot more attention than that.--Thank you for the reminder.---Brian

 

[Cogsy]

I don't clean my lathe overly much either, although I'm trying to get better work habits in general. I think what tornitore45 was hinting at was the grinding grit that would have come from your grinding operation. Likely hardened metal dust and abrasive from the grinder. It would make a fantastic grinding paste for your lathe ways, etc. Most people cover everything possible up with rag before grinding on the lathe.

 

[goldstar31]

My two pennorth? Lathes and all machine tools suffer from grit and turnings becoming trapped under sliding parts and arguably, the bit that suffers most is under the saddle. Well, ALL the ones that I have come across. If there is a gap- no matter how small- the pressures will physically force the saddle down onto the ways. Clearly, you have a new cutting tool that is under the cutting tool.

Today, it is worse! If there is one of these Turcites or Moglices or Devcons - to name a couple or four- the assorted abrasives and turnings will embed themselves into the soft medium. Can things be worse? Let me assure you that cast iron is yet another and possibly more serious problem.

My take- of course

Norman

 

[tornitore45]

Yes, is good practice to cover, before, and clean up after either grinding or machining cast iron, that is if you want your machines to last.

I am a little compulsive (some say a lot), I clean the shop and the machine often because I can not think and operate in the mess and the chips all over.

 

[MCRIPPPer]

would this method be accurate enough to cut tapered holes to match with a tapered part and transmit torque without a key? i want to make a flywheel for an engine with a tapered crankshaft (12mm diameter, and 5:1 taper) and also a clutch output with the same taper. the flywheel has a key to set timing, but the clutch side relies on the friction of the hardened steel crank and the aluminum tapered bore.

 

[bazmak]

Its easier and normal practice to make the male fit the female.Would work
but how accurate would the d bit be compared to the the existind shaft

 

[goldstar31]

would this method be accurate enough to cut tapered holes to match with a tapered part and transmit torque without a key? i want to make a flywheel for an engine with a tapered crankshaft (12mm diameter, and 5:1 taper) and also a clutch output with the same taper. the flywheel has a key to set timing, but the clutch side relies on the friction of the hardened steel crank and the aluminum tapered bore.

I'd have a think- and then another. I recall removing a clutch on a 997 Mini Cooper which had been put on at 140lbs/feet----------------and had fretted.It took a 1" BSW puller and a 14lb sledge hammer to move it- with 2 of us. One a blacksmith and the other the son.

My take is that one laps the two to a blued fit - and then inserts the peg-before putting in the bolt.

I have been following the discourse with interest and one thought is that it is not normal to trust the so called protractor on a top slide.I would have used Pythagorus and his trusted sine bar. The hypotenuse is ideally 10" but I settle for my 5" one. One of my old mates put one(10") on the back of his Myford and off set by a quarter of an inch-- and arguably got better Morse tapers than Mr Morse's own mob.

Frankly, One uses in model practice a setting bar( homemade of course) which is 10" exactly and with two disks to make the hypotenous - and THEN set the top slide to follow the imaginary triangle. You can do it with a small boring head- with round ended centres in the chuck end and the boring head. Yes, you can use female ends with ball bearings but it is fiddly. I've reached an age when my balls are difficult to find:hDe:

 

[MCRIPPPer]

these parts need to fit an existing shaft with the taper already made. its a mass produced small 2 stroke engine, costing only about $150 for the cheapest ones. so i doubt there was any lapping going on. if i set up my taper attachment using a dial indicator on one of the crankshaft tapers, would that produce a reasonable accuracy? i have machined MT2 tapered shanks for my drill chucks and other attachments that work great, but have never made a tapered hole.

 

[goldstar31]

It's school boy maths. We were reminded of the :-
Squaw on the hippotamus hide is equal to then sum of the squaws on the opposite two hides.

or if you want the highbrow version, it is the 6th Proposition of Euclid.- the solution of right angled triangles.

And the exciting bit is the proof

QED

Norman

 

[MCRIPPPer]

i prefer using trig functions.

 

[Charles Lamont]

If you set the existing crankshaft between centres and a use DTI to set the slide round to match the taper (small end towards the headstock), you wont need any trigonometry. And you can bore the hole without needing to make a reamer. Check it with blue before you take the job out.

 

[MCRIPPPer]

well i made a d bit, but have not hardened it yet (made it out of O1). put crankshaft in lathe, indicated and adjusted taper attachment, but taper, made small tweak to get it cutting a PERFECT fitting taper. (i was amazed when i put some prussian blue and it transferred nearly 100% after a quick polishing with some worn out 600 grit!!!) milled it almost half way leaving .002"+ on thickness. did a test cut on some aluminum 6061 and it cuts a beautiful tapered bore that fits perfectly on the crank. i did notice it didnt fit at first before the bit made its way through the part out the other side. maybe it needs a bigger pilot hole. but this worked great!

 

[bazmak]

Love it when a plan comes together