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Turning job on Acorn (How to)
Posted: Fri Apr 08, 2022 8:55 pm
by dmbgo
Hi, A little bit of time has passed since I setup my lathe with an Acorn controller, ball screws and servo motors. I don't come from a machining background, and in the past have relied on asking questions with regard to accomplishing particular things. This has always worked

in the past.
I can turn, bore and thread things on my lathe (not necessarily the best way, but it generally works).
There may be a more specific forum where I could ask this question, and if there is, please feel free to suggest forums.
Here is the question:
I need to make the axle spacer in the photos, for a vintage motorcycle that I am restoring, but I'm not sure how to go about it.
I can easily turn the outside diameter and bore the hole to the correct size, but I'm not sure how to attack the wide groove in between the two flanges?
Should I just do a wide slot with my parting tool? I have had limited success using this for parting operations in the past.
Re: Turning job on Acorn (How to)
Posted: Fri Apr 08, 2022 8:59 pm
by dmbgo
Here is the parting / grooving tool on the lathe.
Re: Turning job on Acorn (How to)
Posted: Fri Apr 08, 2022 9:00 pm
by lavrgs
Is the groove functional? i.e. clearance...If not don't cut it. There are better tools than a parting tool, but you'd need a left and right to get the two inside corners
Re: Turning job on Acorn (How to)
Posted: Fri Apr 08, 2022 9:05 pm
by dmbgo
The groove doesn't do anything, it is only cosmetic, or weight saving. I just want to make my piece as close as possible to the original.
When you say not to cut it, if it's not functional, what do you mean? I thought the easiest way to replicate it would be on the lathe.
Re: Turning job on Acorn (How to)
Posted: Fri Apr 08, 2022 9:22 pm
by tblough
If the wide groove serves no function, then the easiest solution is to just skip that feature in your replacement part.
If you want to put the groove in, then you can do it with your parting tool. The Intercon groove feature is what you want.
Re: Turning job on Acorn (How to)
Posted: Fri Apr 08, 2022 9:34 pm
by dmbgo
Thanks Tom, I thought that the Intercon groove feature would be the way to go, but I also thought I'd ask, In case case there was a different solution.
The groove serves no functional purpose, but I want the parts I make to be as close as possible to exact copies of the original.
It looks like I'll have to get better at grooving

.
As a starting point, (I'm using mild steel bar to make it from), what CSS and depth of cut would I use with my 2mm parting / grooving tool pictured above?
Re: Turning job on Acorn (How to)
Posted: Fri Apr 08, 2022 10:27 pm
by dmbgo
Here are the settings that I put into my grooving job, I'm using MM measurements.
Is this correct? I'm assuming that increment means the cutting depth when talking about diameter, and the step over amount for the tool when talking about width.
Re: Turning job on Acorn (How to)
Posted: Sat Apr 09, 2022 1:49 am
by suntravel
The tool you are using is only for cut off. You need some tool for groove-turn like this:
https://www.iscar.com/Ecatalog/item.asp ... =1&lang=EN
On small lathes grooving can make ugly vibrations, ways to fix this:
Cange the compound slide to a solid tool post:
If spindle bearings are adjustable, check and give them some tension, no play.
Check the other slides and correct them to a minimum of play:
If this is all done grooving in mild steel will work with around 0.04 F/R and 80 CSS in metric units smoothly
Uwe
Re: Turning job on Acorn (How to)
Posted: Sat Apr 09, 2022 2:48 am
by suntravel
Program for groove-turn using Intercon profile :
Uwe
Re: Turning job on Acorn (How to)
Posted: Sat Apr 09, 2022 3:42 am
by dmbgo
Thank you Uwe, I have been chasing issues with both cutoff and now grooving. I did manage to cut a groove on my second try (with different settings to those I posted earlier). I will look closely at your post tomorrow, it's knock off time now
