Question about facing

[coolgoose]

Hi guys,


I have started working on small engine project and did my first turning and facing operations on the lathe. Turning gave a good smooth finish on the aluminum bar that I am planning to make a cylinder. However, facing is the one that I have trouble with. I haven't obtained smooth finish after facing. I have attached the pictures of the surface I obtained after facing and arrangement I used on the lathe. I have set the compound to 30 deg and used a carbide insert cutting tool "AR". Could you please let me know what I am doing wrong? Also, the proper way for doing facing on the lathe. I have some videos on youtube but I guess I am still missing some information


Thanks guys,
Sri.

 

[kvom]

Is the toolpost fixed to the compound such that you have to turn the compound to align the insert?

Your pics are a bit blurry, but it looks as if the insert isn't centered vertically. If the insert is sharp, then fast RPMs and a slow feed should get a good result. If your cross slide is powered, then use that; if not, try to turn the dial steadily.

 

[Ken I]

What clearance angle do you have between your cutting edge and the workpiece ?

Too large produces a "gramaphone record" groove - too small and you will rub - the other problem can be the swarf being dragged in between the tool and the workpiece - change tool geometry (more top rake - less front clearance) or feed rate etc to get the swarf clear.

What are you cutting with - its not clear in photos ?

You don't need to swing the compound (top) slide. You only need to set the angle by swinging the toolpost.

You normally need about 5-8° clearance.

Ken

 

[krv3000]

HI are you yousing any cutting oil aluminum can build up on the tip of the cutting tool and give you a ruff finish + the speed of the lathe + the speed at which you are feeding the tool in and the grade of aluminum all play a part in the finish you will get regards bob

 

[BillC]

Sri,

Turn your compound around toward the front of the cross slide to 30° so that when you advance the compound you are infeeding the tool to the center of the work. You also appear to have the compound slide too far back where its dovetail is less than half engaged. That will lead to flexing of the compound and allow the tool to move. Keep as much of the compound slides together as possible. You may be feeding a bit too slow too. Carbide is normally negative rake and not too good for aluminum without some sort of lubricant of coolant so try a high speed tool ground with positive rake with the cutting edge honed very smooth.

You'll get it. Facing is a compromise in feeds and speeds since the farther in to center you are the slower the cutting speed....

BillC

 

[mklotz]

In addition to everything suggested above:

Try switching to an HSS tool with a generous radius on the cutting edge.

Perhaps the clarity of your pictures can be improved if you use the macro function on your camera.

 

[coolgoose]

Thank you everyone for all the advice! This time I took some better pictures of the finish and the cutting tools I tried. I used both carbide insert one and HSS bit and obtained the same result. I am trying to face Aluminum 6061-T6511 Bare Extruded Round rod.

Can anyone post a pic of facing tool and their setup for doing facing ?


Sri.

 

[coolgoose]

Oops! forgot to attach the pics in my previous post

 

[Jasonb]

When feeding the handwheel don't crank it round with the handle as this can lift -lower-lift the cross side. Instead use both hands on the rim and try to get a constant steady feed.

Its a bit hard to see from the photo but is there a small pip on the end of the work as it looks like the tool may be cutting a bit high.

I would also say both those tools are right hand turning ones, use the opposite hand with teh tool shank parallel to the lathe axis

The shine on the surface does not suggest picking up of teh surface but a little cutting fluid will help

J

 

[coolgoose]

Thanks Jason for the advice on the cranking the handwheel. I am cranking the using the handle. This time I will try using both hands on the rim with constant feed.

I noticed the pip in the center. I will adjust the tool height this time.

When you said to use opposite hand tool, do you mean the one I have attached in the picture? Please forgive my noob questions. I am new to machining

 

[Jasonb]

Yes, thats a Left hand tool but use it as if the picture was rotated 90degrees

 

[Niels Abildgaard]

Use just a little alcohol (not booze but 96%) as cuttingfluid and crank much slower if You do not have powered cross feed.

 

[steamer]

Another easy to apply lubricant for aluminum is WD-40....which is mostly Kerosene....which is about all it's good for.

Generally keep your speed high with aluminum.

Jason's and others comments about lifting the slide and steady feed all apply.


Dave

 

[coolgoose]

Thank you Jason, Neils & Steamer. I will try with your suggestion today and let you guys know the outcome. I have WD-40 with me so will try with that as cutting fluid.

 

[picclock]

Hi coolgoose

I think the problem may be that you do not appear to have a carriage lock. Without one any load on the carriage will allow it to move causing the problem. This will not matter much for turning but for facing every little bit counts.

For my lathe I drilled a hole in the carriage (it may have already been there) between the ways and used a piece of threaded scrap and a screw to clamp onto the underside of the bed - the same way that the tailstock does.

There are other designs that clamp on the front of the ways, but you really need a mill to make them easily.

HSS tooling is the way to go, ensure the tool is close to the holder to prevent flexing. Also tighten the compound and crosslide gibs as any slop there ensures poor results.

I work a lot with steel and a few months ago replaced the compound assy with a solid block of 2x2 steel. The rigidity improvement is astounding. This is the reasons I still use the original toolholder.

It has various holes and overhangs so it can be mounted in 4 positions.

Hope this is of assistance.

Best Regards

picclock

 

[coolgoose]

It worked I finally got a smooth mirror finish! Thank you Jasonb for telling me to use left hand tool. I used left hand tool and some WD -40 for cutting oil and it did wonders. Thanks Steamer for advising me about WD-40


Thank you picclock for showing me the pictures of carriage lock. Yes I do not have a carriage and lock and now I will start making one for me

I would have attached the picture of end result (successful one) but by this time you guys have already know that I am not that skillful when it come to taking picture

Thank you everyone for your response in this thread. You guys rock :bow:

Sri.

 

[steamer]

That's about the only good use for WD-40 I've found other than dissolving light surface rust...

Glad it worked out..

Dave