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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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measuring play in quill+spindle of milling machines & drills
rec.crafts.metalworking
measuring play in quill+spindle of milling machines & drills I'm hoping that some here have measured the play in the quill+spindle of bridgeport & equivilent millers, which will be a deciding factor when I buy one in the future. The measurements that I have made were by chucking a 10 inch piece of bar stock and pulling 10 lbs left then 10 lbs right at the end with a spring scale with the quill lock, when present, loose. A dial indicater set on the spindle indicates the play. A small bench size drill press, a $60 version, showed 13 thousandths of an inch play, 8 for a full size and heavier drill press, and 5 for a spanking new mill/drill from Harbor Freight. The last omitted the scale which leaves it a bit questionable. If anyone has made equivilent measurements, posting the results here would be greatly appreciated. Hul |
#2
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measuring play in quill+spindle of milling machines & drills
Hul Tytus wrote:
rec.crafts.metalworking measuring play in quill+spindle of milling machines & drills I'm hoping that some here have measured the play in the quill+spindle of bridgeport & equivilent millers, which will be a deciding factor when I buy one in the future. The measurements that I have made were by chucking a 10 inch piece of bar stock and pulling 10 lbs left then 10 lbs right at the end with a spring scale with the quill lock, when present, loose. A dial indicater set on the spindle indicates the play. A small bench size drill press, a $60 version, showed 13 thousandths of an inch play, 8 for a full size and heavier drill press, and 5 for a spanking new mill/drill from Harbor Freight. The last omitted the scale which leaves it a bit questionable. If anyone has made equivilent measurements, posting the results here would be greatly appreciated. I cobbled a massively abused Bridgeport 1-J head onto my ancient round-ram Bridgeport mill some years ago. I did some checks on it when I was done. I got about .001" total back and forth movement when pushing about 50 Lbs one way, then the other way on the spindle. I was measuring with a magnetic mount indicator stand clamped onto the main head casting, so I was only measuring quill+spindle radial play, not any flexing of the head to base component stack. This amount of play is the displacement of oil from the bearing balls, and will be zero when the bearing is spinning. I can't find any movement at all in the quill. Unless horribly worn, the Bridgeport quill is a very fine fit, and rarely gets loose. The spindle bearings can get worn out, and they can be pretty expensive ($300 - 700 a set.) But, it is much easier to check them by listening when they are run. If they sound rough, diesngage the direct-drive clutch and try again. The motor and backgear bearings are cheap and easy to replace, so don't reject it is only the small bearings are noisy. You can spind the spindle by hand when the direct-drive clutch is open, and then ONLY the spindle bearings will be turning, so if it sounds OK then, it should be fine. Jon |
#3
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measuring play in quill+spindle of milling machines & drills
On Thu, 10 Jul 2008 22:44:21 +0000 (UTC), Hul Tytus
wrote: rec.crafts.metalworking measuring play in quill+spindle of milling machines & drills I'm hoping that some here have measured the play in the quill+spindle of bridgeport & equivilent millers, which will be a deciding factor when I buy one in the future. The measurements that I have made were by chucking a 10 inch piece of bar stock and pulling 10 lbs left then 10 lbs right at the end with a spring scale with the quill lock, when present, loose. A dial indicater set on the spindle indicates the play. A small bench size drill press, a $60 version, showed 13 thousandths of an inch play, 8 for a full size and heavier drill press, and 5 for a spanking new mill/drill from Harbor Freight. The last omitted the scale which leaves it a bit questionable. If anyone has made equivilent measurements, posting the results here would be greatly appreciated. Hul There should be very close to zero play. Not more than a few tenths between the quill and its housing, and none between the spindle and the quill. What you've been measuring is play plus deflection. If you were to plot your indicator reading vs. force applied, the play would appear as a steep line starting at the origin; the elastic deflection would be a relatively gentle and more or less straight slope. The knee where the two parts of the curve join represents total free play. In other words, play is the parts rattling around when small forces are applied; after the free play is taken up, and you apply more force, you're elastically deforming the machine. Measure the quill play with the indicator base on the quill housing and the point applied to the quill close to the housing. Try it with the quill both locked and unlocked. Stick the indicator base to the quill to detect spindle looseness. As much as possible, you want to isolate what you're trying to measure. The spindle runout, measured on the inside taper or with a known good collet and pin, should be less than about 5 tenths. Perhaps a bit more or less depending on what sort of work you expect to do. A good BP spindle will be less than about .0002, though more may not be a problem for non-critical work. Any play in the spindle bearings in a mill is likely to cause trouble. -- Ned Simmons |
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