How do I cut this - angle/bevel/chamfer?

[zeeprogrammer]

This is a picture of two parts I need to cut. I've done tapers but I can't get my head around this. The first is a cylinder. The second is a cross-section of a flywheel. Both have similar cuts but from two different directions (the first as a turning operation and the other like a facing operation).

The instruction booklet (for those of you following the thread on the open column launch engine) is silent about this.

The 1st part requires angles of 45 deg and the 2nd part is 30 deg.

I'm thinking it should be 'simple', and maybe it is to the knowledgeable ones here, but if it's more than two types of operation...it ain't simple to me.

Help would be greatly appreciated.

I tried doing an attachment...but when I hit post...my browser went blank and didn't come back. I'm hoping I'm not asking the same question twice.

Thank you.

 

[bearcar1]

Hi Zee', If those cuts are relatively shallow, <.250" (and I suspect that they are) you could grind a cutter bit to the required angle and with it mounted in your cross slide at 90* to the part, merely perform a plunge cut to depth and then machine out to the required diameter. There are other methods but this is along the lines of the KISS actions. Good luck, and it appears you are progressing well on your OC engine.

Cheers

BC1
Jim

 

[zeeprogrammer]

Hi Jim,

Thanks for the quick response and the compliment on the OC engine. Good progress for now...going to slow down a bit while I wait for more tools...already itching to start another engine. The recent posts on the Stuart V10s and some beam engines have me drooling pretty bad. Those are the engines I remember as a kid that helped put me where I am now.

Yes you're right. The cylinder is 0.125. The flywheel has 0.13 and 0.25 (due to a boss). So I'm back to grinding a tool eh? Guess I can't/shouldn't avoid it.

'merely' huh? :big: :big: :big: Someday yes.

Thanks Jim.

 

[mklotz]

With all due respect to Jim, I wouldn't recommend a form tool due to the high probability of chatter on a small lathe.

The angles on the topmost piece can be cut by angling the compound which minimizes the chance of chatter. Rough out the center cylindrical section first with a parting tool, then cut the half cone sections and, finally, trim the cylindrical part to size.

For the flywheel cut, there aren't really too many options. Plunge in and take very small cuts.
The trick here is to grind relief on the tool so the underside doesn't rub and cause chatter.

 

[Tin Falcon]

the other option for short tapers with relatively large angles is to use the compound on the lathe.
Tin

 

[zeeprogrammer]

Thanks Marv and Tin.
This seems to confirm my suspicions.
Guess I'll take the plunge :big:
Thanks again. You'll see the results in the OC engine thread...eventually.

 

[bearcar1]

It is as I said, "there are other methods" ........ however, smaller machine or not, the careful and judicious use of a cutter with the desired angles ground on it will yield good results for a novice. Start at the midpoint of the work piece and proceed to either side, then return to the mid-point, increase the cutter depth and machine from the center to the end points once again. Continue until the desired depth is reached. No fooling round with the top slide etc.

BC1
Jim

 

[Foozer]

Thanks Marv and Tin.
This seems to confirm my suspicions.
Guess I'll take the plunge :big:
Thanks again. You'll see the results in the OC engine thread...eventually.

Grinding a bit and sneaking up on the finish will work, it is the chatter that might bite you. But then sandpaper is your friend On your example, the first one, I can get away with the sneak up to about a 0.150 +/- depth without chatter, slow and easy. the full width side to side and each pass I just creep the bit to just meet the previous angle cut. For the times I want to be spot on , in the infield at least, the overall width of cut is slightly undersized and then use of the compound to finish up the angles. For me at least, it is important not to remove the part from the chuck at all. The part never goes back exactly on axis. So its a trial to ensure that there is room to accomplish the steps without having to move the part itself.

I like the form tool approach, my little lathe however, has its own view on that subject, sandpaper and files are your friend.

Clear as mud I know. . .

 

[scoop]

Don't forget that if you get a chattered finish using a form or parting type tool it can be a saviour to just put on a small cut with the chuck stationary and then just turn the chuck by hand to get under the chatter to finish the last couple of thousands.
saved me a few times now as removing chatter with abrasive paper is normally a pain.

good luck Steve C.

 

[zeeprogrammer]

Hi Jim. Thanks very much. Would you clarify what you mean by 'No fooling round with the top slide etc.'?

Foozer and Jim. Yes. I'm getting very acquainted very sandpaper.

Thanks all. Very helpful.

 

[bearcar1]

Zee, I do not know what lathe it is that you are working with but the top slide (also referred to as a compound slide) sits atop the cross slide, the section of machine that moves the tool front to back. The top slide's angle of attack can be adjusted as needed, thus allowing the operator to move the cutter into and out of the work piece at an angle without having to use the normal crossfeed which only moves parallel to the chuck. I hope that this is an adequate expaination and that it makes sense to you. By using a cutter ground to the desired angle, you would not have to mess around with setting the top slide in opposite directions to achieve your goal. Tool chatter can develop but using very light cuts and proper spindle speed will usually overcome this problem. (usually)


BC1
Jim

 

[Dhow Nunda wallah]

Zee, I guess by your moniker, you are a programmer.

Bite the bullet, just like your first steps in writing code. (BASIC FORTRAN,COBOL, Pascal, C.........?)

Get yourself some HSS (high speed steel) of a convenient size for your toolpost.
If you don't already have one, get a cheap 6" bench grinder.

When you've got the above, throw away the "fine" wheel on your grinder and purchase a quality white wheel.
(Norton springs to mind, but I'm not going out in the rain to get the number)

With a good wheel, a solid toolrest and some nice fresh HSS, tool grinding becomes a joy!

Don't worry about "spoiling temper" or other rubbish!

You can produce a custom tool in literally minutes.

Remember the vacu-video method, suck it and see!
What do you have to lose, apart from your time? (and that is time well spent)

For the most part, my paid work is in 316 SS, I use nothing but HSS tooling, no top rake and flood suds.
All of this on a little Jet 9x20 lathe.

Go forth and grind

Regards,
Lin

 

[zeeprogrammer]

Thanks Jim. Yeah I've played with the angle of attack and experimented with doing tapers. But this was a steep angle and worse...kind of close to the chuck. I played with some setups last night. I think I'm going to try grinding a tool with the desired angles and take light cuts as you suggest.

Which leads me to...

Thanks Lin. Yep. What you said. Thanks for the encouragement. BTW...nowadays it's 90% 'C' and an insignificant amount of assembly. I'm an embedded engineer. The other 10% is C++ for writing PC tools. Others long long ago.

...just like your first steps in writing code...

Yes...but my knuckles do not tremble at a keyboard. :big:

 

[zeeprogrammer]

Well that was pretty much a disaster.
Ground a tool.
Ugly.

The sound was horrible. Not a chatter so much as it sounded like the metal was screaming in pain. Enough to make me wonder...'can metal feel?' (of course not).

Post mortem...

Not sure why the cranking the top slide handle didn't do anything...but noticed I was at the end of travel (to the left).

The tool...to put it politely...was "*&%#$%^@". The tip looked all messed up. Like brass was welded to it. (Should I patent that?)

Using the carriage hand wheel to make cuts has so far always been a bad idea except for the roughest of cuts.

Switched to a carbide insert (and reset the travels). What a difference!!! That's what told me it was my tool.

So I'm lousy at grinding tools. Real lousy. No doubt as lousy, if not worse, as anyone who first starts grinding their own cutters.

Unfortunately I can't say I'm real excited about getting better at it despite what others like. I want to make something...not so much to make something to make something.

:rant: :rant: :rant:

But don't get the wrong idea...I will no doubt try again...and again...and again. I :rant: may :rant: be :rant: upset :rant:...but it's not stopping me. (I'm sitting here with a ;D on my face.)

I'm probably more upset that the purpose of the thread showing my project (the Open Column Launch Engine) won't be the thread I had hoped it would be.

All right. Apologies. Everyone has their day (or days). I love this hobby...and this forum is great.

Now I'll go away and think about how to proceed.

 

[mklotz]

Turn the machines off and mix yourself a 15:1 martini. While you're sipping it, take a few photos of the tool tip. I know that nobody likes to show their mistakes but it's impossible to establish the problem without seeing the offending item.

You'll just have to get used to the make a tool to make a jig to make a tool to use to make just one cut on the part. It's inevitable and we all do it. There have been times when I was so deep in the sequence that I literally forgot what the final objective was. It's sort of like programming deeply nested loops.

Two other things bother me. Grinding should not be producing so much noise. Were you using the tool rests or holding the tool free hand? How about a picture of the grinder?

You should be able to turn by advancing the carriage with the handwheel. If the lathe cuts satisfactorily with the power feed, using the handwheel should work as well. Perhaps the cut might not be as smooth as under power, but by going slowly you should get at least reasonable results. Maybe you're trying to go too fast.

 

[bearcar1]

Hi Z'. I am sorry to hear that your first attempt to grind a cutter was unsuccessful. And yes, metal does have 'feelings', I mean c'mon, how would you feel if someone was applying tremendous amounts of force on you to separate yourself from a comfortable existence? :big:
Anyway, from the sounds of it (no funnies intended Rof}) the clearances were not ground properly on your cutter and the metal was not being cut from the stock but was being eroded away by friction, not a very good thing unless you were a sander or grinding wheel. ;D AFA the grinding of cutters, there is only one solution to becoming proficient at it and it as with anything else, practice. Sorry old boy but sooner or later, you are going to have to do it and it is best to get it over with in your early stages. In machine shop class at the UofI, we spent an entire week of classes doing nothing but grinding cutters for different applications. I never got so sick of doing something in my life, but when it was all over, I could grind a cutter for any material and any application imaginable. It is an art form and should be practiced to become good at and also to continue to be good. Were you finally able to get your piece finished to your satisfaction is the important thing here. If not, you know there is always knitting to fall back on as a hobby. It is said to be relaxing and isn't nearly as messy as machine work. Just something else to ponder over while you pass the hours away grinding cutters. Rof} Rof}

 

[zeeprogrammer]

Turn the machines off and mix yourself a 15:1 martini. While you're sipping it, take a few photos of the tool tip. I know that nobody likes to show their mistakes but it's impossible to establish the problem without seeing the offending item.

You'll just have to get used to the make a tool to make a jig to make a tool to use to make just one cut on the part. It's inevitable and we all do it. There have been times when I was so deep in the sequence that I literally forgot what the final objective was. It's sort of like programming deeply nested loops.

Two other things bother me. Grinding should not be producing so much noise. Were you using the tool rests or holding the tool free hand? How about a picture of the grinder?

You should be able to turn by advancing the carriage with the handwheel. If the lathe cuts satisfactorily with the power feed, using the handwheel should work as well. Perhaps the cut might not be as smooth as under power, but by going slowly you should get at least reasonable results. Maybe you're trying to go too fast.

The joy in showing your success is that someone will learn how to do it.
The joy in showing your failure is that someone will learn not to do it.

I have no problem talking about my boo-boos, whether stupid or not. Happily, this forum does not mind either.

Unfortunately..I'm on my second (third?) 15:1 martini (kinda missing the wife a little). What's the :1? The onion? Maybe the glass? What do you mean 'mix'? It's vodka and ice for me...and I'm unhappy taking the time to get the ice.

Here's a pic of the tool...hopefully it shows enough...

The noise wasn't from the grinding (a $50 Ryobi from Home Depot). Other than doing a lousy job of it...no problems. The noise was from using the tool. (Remember...I'm on martinis right now - not responsible for what you read into that sentence.)

But you're absolutely right. Probably the biggest mistake anyone makes is going too fast...and I'm the biggest offender.

As far as the carriage...you're right...that's what I meant. Cutting under power gives better results.

Lastly, "sort of like programming deeply nested loops"...unfair ;D...that's poor design...I don't do that and question the engineer if I see it in a design/code review.

Thanks Marv. A lot.

 

[zeeprogrammer]

Hi Z'. I am sorry to hear that your first attempt to grind a cutter was unsuccessful. And yes, metal does have 'feelings', I mean c'mon, how would you feel if someone was applying tremendous amounts of force on you to separate yourself from a comfortable existence? :big:

Are talking about my family? Or the metal? :big:
The thing about any attempt is that I know it's never completely unsuccessful. It's just :rant: :rant: :rant: frustrating. Rof}
Yep...try try again.
Funny you mention knitting. It was on my list of 'is this a hobby for me' several months ago. Don't laugh...I could've been another needlepointer...what was his name?...the football guy?...Rosey! Luckily...I found machining. Whew.

 

[Foozer]

Unfortunately..I'm on my second (third?) 15:1 martini (kinda missing the wife a little). What's the :1? The onion? Maybe the glass? What do you mean 'mix'? It's vodka and ice for me...and I'm unhappy taking the time to get the ice.

Here's a pic of the tool...hopefully it shows enough...

Replace Vodka with Tequila, no ice

What did you grind the bit from? Only red bits I have are those carbide tipped ones that I could do without. Light cut and they squeal like a scene from "Deliverance." I take it the bit had a point until it "burned off".

Like its said, it takes practice to grind a bit. Did you try and round the point over and inadvertently lose the angle to it, I've done it, so instead of having a cutting edge the bit presented a flat surface? Bit above center? Hard to see from the photo, catch one from the business end, side view.

Bob

 

[Maryak]

Zee,

Stick with the &#1042;&#1086;&#1076;&#1082;&#1072;. No ice but put the bottle in the freezer for at least 6 hrs. Shot glass full, (if it's at the correct temperature it's slightly creamy), down the hatch and followed immediately by salt cucumber. 3 or 4 of those and you can grind anything to any shape. ;D ;D ;D

On a serious note the tool bit just does not look like HSS to me, what is the grit of your wheel? The music and very soft edge also make me think the same thing.

Best Regards
Bob