hammerscale

Amateur Machinists' Tools, Techniques and Materials

Archive for March, 2015

First Warm Day

Posted by hammerscale on March 31, 2015

The first warm day for quite a long time. I was at the lathe and shortly after starting it remarked to myself how smoothly and quietly it was running. Is it magic? Is it good Gremlins? Did someone add Seafoam to the headstock? Or has the warmth softened up the V-belts?

Perhaps that extra 30 degrees Fahrenheit helps?

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Posted in General, Tools | Leave a Comment »

Cross Feed Screw problems

Posted by hammerscale on March 27, 2015

Following quote is from a relatively recent thread on the Home Shop Machinist forum. The subject matter is the quite frequent “crashing cutoff blade” theme, which comes up a couple times a year.

Your problem may very well be directly related to any play you have in your cross slide screw and has nothing to speed, lubricants or rake angels of your cutting tool.
Most of my parting tools have a positive rake as Dian shows in his above picture, helps to curl the chip and gives a nice sharp edge.
I replaced the cross slide screw and nut on my Clausing for this very reason. It had .080 play in it, I had the same problem your having……. every time I went to part something regardless of material, speeds, feed rate, cutting oils etc. I always crunched the parting tool. I was so afraid to part anything I just quit doing it. The reason was the play in the screw. As the parting tool, especially a positive rake was fed in it would want to pull it’s self into the cut and with .080 of play in the screw it would just dig it’s self in and break. I tried negative rake tools which didn’t work well and still would crunch, neutral rake cut a little better but would also be pulled in and crunch setting the tool height made no difference either.
Once I replaced that screw and nut I never had that problem again. I can part any material at any speed with or without cutting oil and even use the power in feed and it works perfectly, haven’t crunched a parting tool since then, not even my .060 ones.

JL……………

For the complete thread, please follow this link

I can well believe the above is the issue in many problems related to lathe operations. My crossfeed screw has a great deal of play (haven’t measured it, yet) and I’m sure is well past due for a replacement for both screw and nut.

That will be the subject of a future blog post.

Posted in Techniques, Tools | Leave a Comment »