lathe brake& spindle lock

[dgoddard]

Well using that MSC SALE price list to estimate my coarse thread taps, I come up with about $65
Then if I add the fine thread taps that will double it.
Noting that the metrics run about 20% more puts all the taps up around 575
But that is only taps, so just for quickies lets double that to cover the dies, (probably an underestimate and say around $1200 and we don't have any tap wrenches die stocks and miscellaneous stuff yet.

the current price of the Irwin/Hanson 117 piece set I bought is $276, and mine are still going along just fine.
http://www.use-enco.com/CGI/INSRIT?PART ... NO=7209870

I rest my case!

I think I have only bought 4 or 5 taps or dies in size/pitch that this set did not have and that I needed in the past 7 years. I would have no problem recommending this set as a good value for price purchase for any newbie.

For that matter I could not find then, any comparable array of fine & coarse, inch & metric, tap and die sets in HSS though I see that Enco does now have one in their import line, for about $635 but I am not sure if the selection is as suitable and it lacks the smaller metrics and appears to be more of a mechanic's set than a machinist's set.


Anything I wear out in the Hanson set will be an indication that I need it a lot and so I always replace with HSS

I can't believe I have helped hijack my own thread so thoroughly

[GlennW]

It could get expensive if you buy every tap in every size in imperial and metric.

I prefer to purchase only the ones I actually use, so it's not that bad. I also didn't buy them all at once. Collecting tools over a period of time seems less painless. When I have to order something I'll see whats on sale and pick up one or two at a time, so over a period of time there is a decent selection of nice sharp taps.

No right or wrong, as everyone does different types of work that requires different tools, so it's just personal preference. I had a carbon steel set just after I got out of High School and it didn't take very long to figure out that HSS is the way to go, but I have always had a thing about sharp cutting tools and good surface finishes.

That was a masterful hijacking job!

[Dave_C]

Don,

Check out the tap and die sets from Grizzly. They are HSS and go for about $75.00 a set for both metric and imperial. Sizes are 4-40 up through 1/2" in both fine and course. Handles are included!

I bought the Imperial set and haven't broken any of them. They do great for what I need.

I use the 1/4-20 about 40 to one over the rest but nice to have the set when I need them. I have bought some single taps when I needed spiral points as well.

That should help the budget a bit! (Or you can borrow mine when you are up this way) [given the price of gas I think the Grizzly set works out to be the cheapest solution]

Dave C.

[ML]

Back to the brake?

How about an electric brake on the motor?
OR a 3 phase motor with a VFD and braking resistor?

Michael

[dgoddard]

It could get expensive if you buy every tap in every size in imperial and metric. ..... I prefer to purchase only the ones I actually use ...

I don't think there is a single tap in the set I have not used at one time or another. I think the Hanson set has a pretty good array of taps. and i only have had to buy an extra tap just a few times. I have very few occasions to need a tap larger than about 1/2 or 12mm or smaller than 4-40 or 3mm. Although the readouts on my mill and lathe are inch, all the fasteners are metric, and I refuse to bastardize them by drilling or tapping them out to inch sizes.

Check out the tap and die sets from Grizzly

I concur, those appear to be reasonable sets provided the quality is there (and going by your experience it is at least satisfactory). The fine and coarse sized appear t be right but they do not list them in their catalog or on line, But the prices are now $98.95 for both the G9767 (inch) and G9769 (metric) sets. These two sets together appear to be comparable in the selection of sizes to the Hanson set, are HSS, and significantly cheaper. Too bad they were not available when I was looking for a basic set.

Back to the brake?

Good Idea

How about an electric brake on the motor

3 issues,
A. Can I control the amount of braking torque
B. Can it be made to hold the spindle still once stopped
C. How Costly, I am really looking for something that I can build at home with low cash outlay.

a 3 phase motor with a VFD and braking resistor?

Same as the preceeding but this sounds like the most pricey solution of all.

l

[ML]

Here is a quick pick on
http://www.ebay.com/itm/Stearns-Motor-S ... 5182d5bbec

Michael

[dgoddard]

Here is a quick pick on.....

It appears to be a bit puny. At 3/4 of a foot pound. Allowing for the drive ratio that is like applying 1.7 foot pounds braking torque to the spindle at the high speed setting, so stopping a spinning load won't be quick, The 3/8" motor shaft size of the brake should be a give away that this brake is not intended for use on a 2 hp system, With the lathe in lowest speed the torque at the spindle is only about 30 ft lbs. While this is not insignificant it hardly constitutes a "lock" and would require shifting the gearing to obtain that much. It is enough t provide a gentle braking of the spindle however.

I haven't run all the numbers but at the moment I would say that brake is too small by a factor of about 4. If anyone here has an electric brake on the motor of their lathe, I would be interested to know what the specifications of such a brake typically are.

[GlennW]

Mine is electromagnetic brake on the motor shaft, has a brain and a motion sensor that control it, and appears to be in compliance with OSHA and their 3 revolutions to complete stop rule.

It is controlled by the "foreword" "stop" "reverse" lever on the carriage.

It doesn't stop quite as quickly toward the end of the day though, probably due to heat. It's an eye opener on a cold morning though!

I always use the smallest work holding device possible so the brake does not work any harder than necessary.

You will find it inconvenient to have the brake stop the spindle and remain locked, however, as you nearly always need to rotate the spindle for chuck key access. That's why mine has a brain and a motion sensor. It automatically releases the brake when the spindle reaches zero rpm.

It's a fairly sophisticated system. 6hp lathe.

[stevec]

Mine is a neurological brake that allows me to turn the chuck by hand to aid in inserting the key, it also allows me to turn the workpiece while adjusting for runout and sometimes turns ever so slightly as I twist the tap wrench that fraction of a degree before the tap breaks.
It has a "ramp down" feature that varies depending on the speed setting and weight of the workpiece and work holder.
It has no lock therefore preventing breaker trip or motor burn out if the lathe is turned on while in use.
It cost nothing to be fitted to the lathe and requires only the application of a limited number of brain cells, which I have....er, no wait!

[dgoddard]

Glenn & Steve,

Have either of you seen a rating plate on the brake that indicates what its torque capacity is. That would be useful.

However, It would be good to know what sort of work piece it was supposed to stop. For instance, on Glenn's 6 hp Lathe, It would have to be one horse of a brake to stop the maximum weight work piece if it were for instance in the form of a thick wall tube that was at the limit of the swing of the lathe.

I would be curious to know how one measures the OSHA 3 turn rule. (I thought it was 2 turn) because obviously with the largest chuck and workpiece, the problem of stopping it sets pretty hard, especially when the geometry of the part is such as to maximize the Mass Moment of Inertia (which is why I said thick wall tube).

Worst case would be the largest weight the lathe can handle, as a thick wall tube that just clears the saddle gripped by the largest chuck used in internal expanding configuration. with nice big flanges on both ends that just clear the bed. The same weight as a long solid shaft would be a piece of cake by comparison.

[stevec]

I'm pondering a psychotic break!

[GlennW]

I have no idea what the torque rating of my brake system is. I have also never looked at it, as the motor has the armature shaft extending from both sides of the case. One end runs the lathe while the other has the brake unit on it. It is buried in the base of the lathe and I believe would require removal of the motor for access to it.

I don't know much about the OSHA rule, other than it is 2 or 3 revolutions to a complete stop when the E-Stop is pressed. A lathe, or other machine tool where the work rotates, would be an interesting example as there are varying load characteristics.