I want to turn another external circlip groove on a Bilstein car shock absorber. The lower spring seat is fitted over a square section circlip, in a tightly machined recess, to stop the circlip getting dislodged, and i want to raise the ride height of the car by machining on my lather another groove a little higher up. The clip is about 2.5 mm thick, and the groove about 2.5 mm deep, allowing the 4 mm wide clip to stick out a bit. The shock absorber body is mild steel, and I will use a centre point on one end to stabilize the set up. My concern is how to make a suitable lathe tool to turn a new groove, and at what height to have it. I can experiment on some scrap, but any tips are appreciated. Thanks.
Are you certain the place where you want to cut the new groove is thick unough to "take" a 2.5 mm deep groove?
Just asking....
If it isn't, how about just machining a tubular spacer(s) of the right length with one end which fits over the circlip in its original location and the other sized to fit into the bottom of the spring seat?
Thanks for the warning, I know the tube is of uniform thickness as i have cut them up before. I could indeed make a stepped spacer, but would like to know how to just machine another groove. The making of the tool and its height and feed are what I am concerned about. Thanks Jeff.
There are standard grooving inserts available for the widths you need for the circlips. Kennametal topnotch comes to mind but there are several others. Call kennametals 800 number for more help. Get the number from 800 information. I am not in the shop now or I could give it to you.
*Please*. The machine is a "lathe", not a "lather", and what you do on it is "turning", not "lathing". I've been watching article after article go past with "lather" in the "Subject: " header, and wanting to post to correct that. Consider this as being that task done.
How large in diameter is the body of the shock? How large is the hole through the spindle on your lathe? Ideally, you should have it chucked so the area you wish to machine is as close to the chuck body as possible.
Assuming that your lathe is too small to accept it this way, is there a center hole pre-drilled in the end of the shock to accept the live center from the lathe?
If not, you will probably have to use a steady rest instead, which clamps to the bed and supports the body of the shock absorber with three fingers which are adjusted to keep it from moving.
Also -- are you sure that the shock body walls are thick enough where you wish to make the new groove? Otherwise, you might weaken it. Check whether the diameter is greater where the grooves are than where you wish to put them. If so, then the wall may be too thin in the new location.
The tool is very much like the O-ring grooving tool which you (I think) just recently asked about, and received a lot of advice.
As to at which height to mount it -- the cutting lip should be at center height as with pretty much all lathe tools. At most, very slightly under centerline for OD turning, and very slightly above for ID turning to make it a little less troublesome with chatter.
Your 2.5 mm thickness is pretty close to 0.100" (actually
0.0984" so a 0.100" thick parting tool could probably do the job nicely. Unlike the previous question about a special O-ring groove, you don't really have to worry about corner radius here -- just go for a square end on the tool.
Or -- grind it from HSS (what I would probably do for the purpose), and just keep grinding and measuring until it is the right width. (It can be slightly narrower back from the tip, to reduce drag on the sides.) The advice about a chipbreaker at the top would probably help, too. Make it just a bit longer than the needed depth of the groove, unless you have other things which could use the same tool and which need deeper grooves.
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