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Tramming PM 833tv
- Thread starter frank13
- Start date
I am a newbie owning a humble EMCO FB2 300 lb bench mill but I have done quite a lot of tramming on the machine so I have some basic knowledge and experience on the subject. I am afraid I can't quite understand your numbers. I am assuming that "ribs" means position references of some kind . If I look at the DTI reading difference between rib1 and rib 4 with Head down Quill up locked , it is -0.004 - 0.0045 = 0.0085 absolute. I agree that this is quite terrible for table flatness, at least a lot worse than that of my mill ( 2 tenths of a thou over 12 inches in X direction ). However, with the head up and quill down locked, it is 0.004 - 0.0035 = 0.0005 which is almost nothing. Why is the table surface height variation affected by the of the position and locking of the head and quill ?
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The house is post-tensioned, but the shed is not. I am on caliche (and it sucks).
The house has done fairly well, but the shed is not nearly as good. And that's with watering the foundation a couple times a week in the heat of summer.
lived in Texas for years. Houston, then Austin where we had a bunch of rock. now I'm where everything is sand. everything here has concrete slab on grade, but post tensioning cables aren't required.
I'd pay a lot for someone to substitute rock or sand under my shop.
- Joined
- Nov 23, 2020
- Messages
- 820
OK I watched your videos and I have a few bits of feedback.
First, the boring bar. Do you have a smaller boring bar to bore with? That bar looks like it barely fits in that hole. Did you grind the bar to get your cutting edge and clearance? Those types of cutters I would simply classify as blanks. Carbide insert boring bars will be easier starting out with, as the geometry has already been figured out.
Lock the table. Gibs are only one area where slop comes into play. lock the table in place X and Y before boring.
Speeds and feeds, cutting geometry etc. Do you have Z power feed? If so, lock the quill and power feed the bore. The PM power feeds do a pretty good job at slow boring. Lock your X and Y axis. Gibs is one half of the backlash equation, the lead screw is the other half.
Invest in some carbide insert boring bars, you can run that boring head WAY faster when its cutting a chip. What you have is fine when you know how to grind it for the material you are cutting. Carbide insert lets you swap inserts easily for what you are cutting.
Edit for additional - How big a cut are you taking on the bore? You can easily take 20-30 thou in a cut, you WANT to take at least 10 thou. You don't want rubbing and burnishing, you want a chip to form. make sure you aren't trying to just take a thou or 3 at a time. with insert tooling you can typically take smaller cuts successfully, especially with honed inserts with a sharp edge.
First, the boring bar. Do you have a smaller boring bar to bore with? That bar looks like it barely fits in that hole. Did you grind the bar to get your cutting edge and clearance? Those types of cutters I would simply classify as blanks. Carbide insert boring bars will be easier starting out with, as the geometry has already been figured out.
Lock the table. Gibs are only one area where slop comes into play. lock the table in place X and Y before boring.
Speeds and feeds, cutting geometry etc. Do you have Z power feed? If so, lock the quill and power feed the bore. The PM power feeds do a pretty good job at slow boring. Lock your X and Y axis. Gibs is one half of the backlash equation, the lead screw is the other half.
Invest in some carbide insert boring bars, you can run that boring head WAY faster when its cutting a chip. What you have is fine when you know how to grind it for the material you are cutting. Carbide insert lets you swap inserts easily for what you are cutting.
Edit for additional - How big a cut are you taking on the bore? You can easily take 20-30 thou in a cut, you WANT to take at least 10 thou. You don't want rubbing and burnishing, you want a chip to form. make sure you aren't trying to just take a thou or 3 at a time. with insert tooling you can typically take smaller cuts successfully, especially with honed inserts with a sharp edge.
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