Bushing hole cutter / reamer - self centering

[stan stocker]

Hi Folks,

While looking at the upcoming weekend workshops at the school, I noticed the bushing class includes making cutters for use in a drill press. One description stated that the drill rod is the diameter of the bushing to use, that the tools are self centering, and only a couple of tools are needed.

I've done a lot of bushing, and have several methods I use regularly, but am always interested in learning new methods. In addition, a friend is just getting started and we are putting together his list of tools.

Does anyone have pictures of this style of cutter or a reference to any bulletin articles or other info? I've made plenty of reamers and cutters over the years and am curious to see the cutter and more importantly the pilot geometry (reliable self centering would be very cool!). Not curious enough to spend the class cost and travel expenses to find out, just curious.

Thanks,
Stan Stocker
Linden, Virginia

[Willie X]

Stan,

I've never seen anything that was rigid enough to 'self center' except a milling machine. A few clock people do indead use mills but I could never justify one for myself.

They may mean 'self center in a round hole'. That's easy enough.

Curious myself, Willie X

[wdonovan]

A thousand years ago a clockmaker who was tutoring me gave me a pair of cutters for bushing work. The first was more or less a spade drill with a round pilot on the end. Maybe a 135° included angle on the cutting edge. No side relief (on OD). Second cutter was also a spade drill with an extended point and a counterbore surface. First drilled out for the bushing, second sized for the pivot and cleaned the thrust surface. For a drill press method, the first is all that is necessary but..... and this is a big but.... you need a set with many different pilot diameters and at least a few different bushing diameters. I have tried to come up with a universally piloted cutter to reduce the number of cutters needed but never could come up with something practical. The only way I know of to center with a rigid machine is a pilot bushing above the plate, clamped to it. It would be centered with a point and clamped the any cutter fitting closely would be centered by the bushing.

Please post back when you find out what they have in mind.

[Joseph Bautsch]

I've used a table top drill press for bushings for years and it's all self centering. You don't need a mill and pre-filing bushing holes is a waste of time. I have the Bergeron drill press holder with the set screw, with Bergeron reamers in the KWM sizes. I use the pointer to line up the plate where I want the hole to be located and clamp it down with the drill press bushing clamp system. There is no sloppiness in the Bergeron holder so there is no lateral movement of the reamer as with the KWM holder. With everything locked in place the reamer will drill a hole exactly where you pointed it regardless of the shape of the worn bushing hole. The D shaped reamer is a self centering type drilling device and cuts the hole exactly where it is pointed. A mill does not add anything to the accuracy of the placement of the bushing. Placement accuracy depends on how good you are in placing the pointer by eyesight and a mill does not improve on that.

[Willie X]

J.B.

Probably not as "exactly" as you may think, unless you have a very good drill press, one with a very strong table and zero run out quil. In short, a drill press that would come close to a small milling machine.

It's that off center hole that all clock repairers have to deal with that presents the problem, or maybe just the definition of "self centering".

The best to all, Willie X

[WT Clocks]

I also use a drill press. Except I use KWM reamers. I do not lock anything down, I allow the plate to float. Everything is always centered. Now if the hole is worn real bad then I center the hole by hand and then I use the correct size reamer for the pivot or I use the Bergeon bushing machine. Now I know there are a lot of people that would stand on their head because of my method of bushing....... If you want a reamer that will center as good as anything could center. I would suggest the KWM system.

[Bryan Prindle]

Yea, I've had to always pre-broach the pivot hole to even out the wear or the cutter will "walk" all over the place. I don't care how carefully you center the cutter it just doesn't seem to work. Now I think if you're skilled enough you could initially just cut the off wear side, but I'm haven't perfected that technique yet. Still working on it. Unfortunately, I've had to fix a few botched jobs (my own clocks). Have a collection of holeless bushings, or sometimes I put an undersize hole bushing in and then push the broach it one way or the other to center everything up. Probably not the best way to do it, but it does fix the problem.

Bryan

[Joseph Bautsch]

Willie X - Unless your eyeballs can measure in thousands of an inch the alignment difference between a mill and drill press will never be critical enough to matter. Now if your eyeballs do measure in thousands of an inch we need to get you in the Guinnes book of world records. The only time it does make a difference is in placing bushings for extremely accurate time pieces and then you will be using CNC to do the placing not your eyeballs.

Bryan - If you properly lock down the plate the cutter will not walk around. I assume you are talking about a standard D shaped reamer as the cutter.

[Jerry Kieffer]

A mill does not add anything to the accuracy of the placement of the bushing. Placement accuracy depends on how good you are in placing the pointer by eyesight and a mill does not improve on that.

Joseph
I will have to respectfully disagree. A Quality Small Mill has several advantages over a drill press for Bushing work. The first one would be that a reamer can be held in a collet with little to no runout allowing the reamer to do its job by reaming a accurately sized hole. The second one would be the ability to locate the proper position of the reamer. I will certainly agree with you on the difficulty of locating the position with the point of the reamer. I have yet to see anyone demonstrate accurate consistent locations with reamer points reqardless of what they are used in. In a milling machine the location can easily again be located because of the use of accurate collets. In this case a Pin Gage of the same diameter as the pivot held in a collet, can be positioned in the plate pivot hole in the exact original pivot location. Because of the accurate leadscrew/handwheel control of a Mill, this can be very accurately and easily done in a few seconds especially under magnification if required. Once located the reamer is inserted in the spindle and the hole is reamed for the bushing in that exact location.

In addition the Mill Machine offers the ability to easily, quickly and accurately re-depth wheels/pinions where bushing location mistakes have been made. I have explained this in the past and will not rehash it again unless requested.

We each of course have our own methods but personally I have used a Small mill for bushing for several years. After many years of trying all other traditional methods it has performed consistent high quality work with greater accuracy than other methods used. However its greatest asset has been the ability to easily and quickly correct poor quality bushing work on troublesome movements both clock and watch.

Jerry Kieffer

[Cactus50]

I have to go with Wt on this one. I use a Bergeron bushing tool, the one with the floating magnets, and KWM reamers. I use the magnets as stands to support the plate by screwing them all the way down so they are all the same height, and the plate can "float". For round holes, 10 seconds and you are on to the next one. If the hole is oblong, the rocking method of cutting the unworn side first takes a little longer, 15 seconds and you are on.. I do well over 1000 bushings a year and have had no problem with centering or depthing on any plate as yet. Maybe today will be the day - who knows. Point I am trying to make is that bushing is like any other skill, if you master the simple hand methods first, any tool assisted method will increase your speed - but you must still provide the accuracy.

[Jerry Kieffer]

Hi Folks,

While looking at the upcoming weekend workshops at the school, I noticed the bushing class includes making cutters for use in a drill press. One description stated that the drill rod is the diameter of the bushing to use, that the tools are self centering, and only a couple of tools are needed.

I've done a lot of bushing, and have several methods I use regularly, but am always interested in learning new methods. In addition, a friend is just getting started and we are putting together his list of tools.

Does anyone have pictures of this style of cutter or a reference to any bulletin articles or other info? I've made plenty of reamers and cutters over the years and am curious to see the cutter and more importantly the pilot geometry (reliable self centering would be very cool!). Not curious enough to spend the class cost and travel expenses to find out, just curious.

Thanks,
Stan Stocker
Linden, Virginia

Stan
I know that the School has been evaluating bushing methods with the idea of putting together a bushing workshop. It is my understanding that at least in part they wanted to offer accurate, practical and economical options for those who are starting out. The methods that you are referring to sound like the methods developed by Al Dodson the lead clock instructor. I have not seen this method in operation . However I recently had a chance to work with Al for a few days. I can tell you that my impression was that he is a highly professional, creative and meticulous individule with many years experience. In addition Al is a very helpful person. I would suggest that you contact the school directly and I am sure you will get the information you are looking for. E-Mail and phone numbers are available under "School" on the main NAWCC Page

Jerry Kieffer

[Joseph Bautsch]

Jerry - I fully understand the method you described in your reply and agree it has more advantages over a drill press. But how many clock repairmen who use a mill also use Pin Gages to set up the alignment of the reamer. For that matter how many repairmen even know what Pin Gages are? I would guess not many. The point in my discussion was the accuracy of sight aligning reamers to drill a bushing hole with a bushing pointer tool on a drill press as compared to doing the same thing on a mill. Doing it that way you lose all benefits of the mill. Your eyesight alignment is no better on a mill as it would be on a drill press and you agree on that point.

[Jerry Kieffer]

Jerry - I fully understand the method you described in your reply and agree it has more advantages over a drill press. But how many clock repairmen who use a mill also use Pin Gages to set up the alignment of the reamer. For that matter how many repairmen even know what Pin Gages are? I would guess not many. The point in my discussion was the accuracy of sight aligning reamers to drill a bushing hole with a bushing pointer tool on a drill press as compared to doing the same thing on a mill. Doing it that way you lose all benefits of the mill. Your eyesight alignment is no better on a mill as it would be on a drill press and you agree on that point.

Joseph
I agree with your statements. However I personally feel the board is all about offering options. When you consider the types of problems that come up on this board on a regular basis, a $50.00 set of Pin Gages could go a long way in resolving many of them. Bushings are a good example. Once bushings have been installed, in many cases they will need to be fit to the pivot. Cutting and smoothing broaches are one method but leave a tapered hole that is difficult to properly fit because of the process. However if a proper sized ground and hardened pin Gage is ground to about a 15 degree angle with a fine stone it is far superior to a cutting broach. See attached photo. The smooth sharp edge will produce a much smoother parallel surface than a rough scrapping (Cutting) broach. After cutting the hole to size it produces a tight fit to the pin Gage shaft, that if you continue to rotate will produce a smoother hole than the rougher smoothing broaches. In addition to producing a proper fitting parallel hole they can be used to produce proper hole alignment parallel to the pivot. This is done by entering in the opposite bearing hole when fitting a bushing to a pivot. The opposite hole holds proper pivot alignment. See attached photo of the dirt works only shown for illustration of the fitting process with a pin Gage installed held by a collet pin vise. In some cases Pin Gages are less expensive than quality broaches.

Jerry Kieffer

[shutterbug]

Jerry - that's interesting stuff! A couple of questions though:

How many of them do you need (for different sized pivots, etc)?
How do you determine the size to use(a formula)?
Where do you get them?

[Jerry Kieffer]

Shutterbug
Pin Gages are generally sold in sets most commonly by .001" steps. For example a typical set may be from .060" to .250" that would contain 190 pins with each one .001" larger than the next one. If for clock work I make sure the pins are at least 2" long. Your work will determine the size range that will work best for you. Pivot hole sizing procedures are the same as if you are using traditional broach methods.
Pin Gages are available from any machine tool supply house such as Travers, MSC, Enco etc. etc. For purposes of clock work all but the cheapest Import sets will do the job.

Jerry Kieffer