Thread: Morse Taper Turning

Thanks for the tips Ashore. I shall endeavour to apply them!
A couple of things I noticed (before the tool went): firstly a heavy feed rate with the tool cut heaps better than going tentatively...I don't have drive on that, just hand wound; and my cross saddle has slop or backlash on the feed winding thread, so the tool post has some shudder:eek:. Maybe locking it off will help, but maybe time to pull it apart and find the problem.

Cheers,

Mate locking the saddle down when parting off was rule No 1 when I did my time
Rgds

Originally Posted by Ashore

The compound slide method you are using is fine it's just harder to get a good finish and the finish on the morse taper is all important , you need a mirror finish if possable as any blemish on either face will transfer to the other and cause damage & eventually slippage , the best bet in my opinion is when you get the male unit finished using a finishing tool then emery paper or wet and dry as smooth as possable use the back of the paper and some very fine grinding paste while still in the lathe to give that final finish

Just a tip. If you use any abrasive to finish a piece while in the lathe or mill catch the debris in a rag laid underneath it to protect the slides etc. This obviousley stops the abrasive geting on the slides and wearing them.

Originally Posted by Mini

Just a tip. If you use any abrasive to finish a piece while in the lathe or mill catch the debris in a rag laid underneath it to protect the slides etc. This obviousley stops the abrasive geting on the slides and wearing them.

Good Call

I finally managed to grind a new finishing tool based on Dennis’s description. I made it out of ½” square HSS bit. I turned a short taper and practiced a few finishing cut at 50 RPM using WD 40.

Definitely the best finish that I got so far.

Is this more or less the finish that is achievable with HSS bits, or should I practice more?

Hi Jan,

Getting there . In the pic can see tool, suggest reduce negative side rake and decrease nose radius 50%.

Will help reduce chatter marks in photo.

Will post later with some photos

Best Regards
Dennis

O f--k it. I just wrote a novel on how to part off correctly and it did not load up:mad: :mad: :mad: .

Sorry Jan but unless you get someone there to show you how to do these various operations you are playing with fire. When I was in my first year of my appenticeship at trade school I had the whole of a compound slide (with tool post still attached) land on the back of my feet. This was from the lathe behind me where a fellow apprentice had fed in the parting tool too fast that it dug in and snap the bolts that held the slide down. I tell u I made sure that I took a spare pair of jocks in after that episode. Never put the cutting edge above or below the centre height. Always use coolant - flood it if need be. Never use the traverse. Apart from tightening the carriage ensure the cross slide is also locked. Never part off with just the width of the cutting tool. Always have the overhang at a minimium. Ensure the parting tool has all the correct clearance angles.

Btw I hope you are wearing your safety glasses when machining?

Best of luck.
David

Originally Posted by Metal Head

. Never put the cutting edge above or below the centre height. Always use coolant - flood it if need be. Never use the traverse. Apart from tightening the carriage ensure the cross slide is also locked. Never part off with just the width of the cutting tool. Always have the overhang at a minimium. Ensure the parting tool has all the correct clearance angles.

Btw I hope you are wearing your safety glasses when machining?

Best of luck.
David

Hi David,

I did a search on “parting” in the metal forum and could not locate a thread on this topic. So if you could find the time and energy to pen down any thoughts on the subject it would be greatly appreciated by me and I am sure many other newbie’s would benefit from it.

My view is that it would be great if someone can start a new thread, just dealing with the Parting Operations. Not having a machining background, I try to be sensible in my approach. Yes, I do ware my safety classes and use the shield on the lathe whenever possible. With all that sense, I still manage to destroy my parting blade. This incident is the reason why I no longer attempt any parting operation on the lathe.

I feel that the input from more experienced people is of great value, and the reason why I absolutely love this forums.

I would also like to hear your views on a back mounted parting tool post, as well as parting tool geometry.

Oh, A tip on writing up long messages: I normally do it on Word and save it as I go along. Then I just cut and paste it into the forums.

Hi Jan,

For cutting tools, geometry depends mainly on the properties of the tool material and the work material. For single point tools, the most important angles are the rake angles and the end and side relief angles.

The back rake angle affects the ability of the tool to shear the work material and form the chip. It can be positive or negative. Positive rake angles reduce the cutting forces resulting in smaller deflections of the workpiece, tool holder, and machine. If the back rake angle is too large, the strength of the tool is reduced as well as its capacity to conduct heat.

Some pics. 1) Tool top without nose radius, roughing tool grind and lap radius for finishing. Cutting edge started on edge of blank this is many regrinds later.

2) Side of tool. Top or back rake just noticable

3) Cluster diamond dresser. I have found this to be the best way of dressing grinding wheel faces, it has 7 diamonds, when used lighly imparts a very fine, line free cutting face to wheel.

4) Dresser

5) Diamond lap. Comes in Fine, Medium or Coarse. Quicker to use than oil stone. Hold tool bit in vyce for stability. For some materials I also lap top and side faces. Can be bought at Bunnings / The Knife Shop.

Earlier link to Hercus Text Book. See book page 70, Fig 178. (Abode 37 veer right) Coolant drip can.

Full flow is better but this or something similar allows 2 hands on compound slide to keep a continuous cut happening, some materials require this. You guessed right, coolant does all the things you mentioned, lubrication as some materials will build up on tool and ruin finish. Flow cools the tool especially when using higher speeds/feeds or large depth of cut but cannot do this effectively if it is brushed or squirted on, and of course aids in washing chips away. (as well as making a mighty mess at times)

The last pic you posted seemed to have some chatter or probaly harmonic pattern marks. (or it could just be the picture) To kill these reduce nose radius and negative leading edge on tool. Centre drill end and use rotating centre. What is youre lathe mounted on?

BTW spotted this but only goes to 7/8" and the small taper head securing screw is not a great idea. Diameter too small and inability to obtain any decent torque with a small allen key.
http://cgi.ebay.com.au/SLITTING-SAW-...QQcmdZViewItem

BTW2 As you are using a draw bar to retain arbour, rough down taper to pre finish size and undercut centre 50% off taper 0.020" deep. This allows front and rear tapers for location and draw bar to secure.

The centre section of taper in your application (draw bar) is not needed, only necessary when no draw bar available and you require self locking capacity that a full morse taper was designed to give.
Hope it helps. At least it will make turning the taper quicker!

Best Regards
Dennis ps Post some pics of lathe.

Dennis,
Thanks again for all the detail. Your last message highlighted the fact (to me) that there is still a very steep learning curve for me ahead.

I have decided at this point that it is less important for me to finish the arbor that I am busy with and more important that I learn as much as I can with regard to the finishing operation. It is a skill that I will need on all future projects as well.

You mentioned that the picture seems to contain harmonic chatter patterns:
I think your right, very likely harmonic patterns. Can a tool chatter so softly that you do not hear it but the patterns are still showing up on the work?

The patterns was also more pronounced at the unsupported / tailstock end of the taper.

You have mentioned various things that I can do to make things better: I will try and do them one at a time and take pictures as I go.

My plan is to first use the existing ½” finishing tool, but this time with tail stock supported.

Then I will make a new finishing tool (My third one). I take it that it can look like the picture you posted but with the cutting tip “radius-ed” slightly? It does not have to look like the finishing tools that I have been grounding up to now? I have been reading up on the rake angles. Am I correct in say that I should aim for neutral side rake, and 1 to 2 degrees back rake? In other words the top of the tool should slant slightly from the cutting tip backwards, but not from side to side across the top?

I will then move into mounting problems. The lathe is mounted/bolted on a base that was sold with the lathe. The base is basically two columns (see picture) made from thin plate steel (1mm). The base is NOT currently bolted to the floor!

I will then try to get some flood coolant going. Is there an oil-based coolant that I can use? I have two young kids, so my time in the shed is very limited and frequently interrupted. I do not have time to always clean up after a session, and would not like water to be on/in the machine for extended periods of time.

Machine Pics:
I bought the AL300 (300x600)lathe from Hare and Forbes. This is from their catalog. You can see the metal base as well. I also bought the dovetailed Z axis, HM45 mill.

Regards,
Jan

Originally Posted by jvdv

Hi David,

So if you could find the time and energy to pen down any thoughts on the subject it would be greatly appreciated by me and I am sure many other newbie’s would benefit from it.

Hi Jan,

Unfortunately time is a precious commodity in my life atm so I don't have the luxury of writing articles like that. May I suggest as you don't have much idea on the various operatons performed on a lathe that it would be worth buying a book that tells you about these procedures.

Or as I have just done is "GOOGLE" the item and you will get some fantastic info like this

http://www.mini-lathe.com/Mini_lathe...ng/parting.htm

Far better than anything I could do. As you will see at the bottom of the page that is does have articles (which include photos) on other lathe procedures.

Regards
David

P.S. It looks like a good machine you have bought yourself there.

Originally Posted by Metal Head

Hi Jan,

Unfortunately time is a precious commodity in my life atm so I don't have the luxury of writing articles like that. May I suggest as you don't have much idea on the various operatons performed on a lathe that it would be worth buying a book that tells you about these procedures.

Or as I have just done is "GOOGLE" the item and you will get some fantastic info like this

http://www.mini-lathe.com/Mini_lathe...ng/parting.htm

Far better than anything I could do. As you will see at the bottom of the page that is does have articles (which include photos) on other lathe procedures.

Regards
David

P.S. It looks like a good machine you have bought yourself there.

Hi David,
Thanks for the link to the parting info and other suggestions. I will keep at it.
Regards, Jan

This is the surface finish that I got with the 2nd finishing tool. As expected the finish is not good (The rake angles are suspect).

I also include a picture of the tip of the 2nd finishing tool. A small pit developed at the contact point, on the tip of the finishing tool as I was taking the finishing cut. I am not sure what caused this, but I guess this is the reason for the radial grooves on the surface?

I grinded a third tool and aimed to get it like the pictures submitted by Dennis. I then rounded the tip and gave it a bit of a hone on an oilstone. I ordered diamond laps as suggested and they should arrive in the next few days.

I then tried the following from the tailstock end:
1)50rpm, WD40, very-very slow feed rate by hand
2)50rpm, dry, faster feed rate by hand
3)50rpm, dry, very-very slow feed rate by hand
4)50rpm, 50-50 Neetsfootoil/Kero mix, very-very slow feed rate by hand
5)Not yet done!

The surface finish with regard to smoothness is a lot better, and I am sure it will get even better if I really hone the tool.

My question: As can be seen in the sections 1 and 4 there are this wavy lines appearing on the finish. I is really quite smooth and does not feel like ridges to the touch, but you can see it.

Is this chatter or harmonics? I have tried to google on this, and have found a web page that suggest that in some cases the pulsing torque of a single phase motor can “phonograph” it self onto the work piece. What the??? The writer suggest that you loosen the belts in the headstock as much as possible to diagnose if the motor is causing this.

I will try that next.

My lathe is also not bolted to the floor, so I guess I still have a few things to try.

Any comments would be appreciated.