A great investment.

[SidecarFlip]

Precision drilling, that's all I was after, plus I wanted to check drill press for run-out and got 25 - 30 thousands from a brand new buffalo drill press, well they made in China and no precision drilling possible when spindle wobbles at such rate. Milling machine, I was thinking to find used Bridgeport, just the prices on them won't come down

I doubt it's the spindle, .020-.030 is a lot. It's probably the drill chuck and thats replaceable. They are interference fit on the end of the spindle, which is tapered (usually a JT taper which is intrinsic to drill chucks).

The chuck might not be fully seated or seated crooked. It's easy to remove (the drill chuck). Take a cold chisel that will fit between the chuck and the end of the spindle and tap it with a hammer. The wedge of the chisel will remove the chuck. Then, you can check the taper to see if the spindle is running out that much (I doubt it is).

Inspect the taper hole in the chuck body and the taper on the spindle. Make sure there are no burrs on either mating parts, if there is, use some fine emery cloth to remove them, clean the bore and the spindle taper with a clean dry rag to remove any grit or oil and carefully re seat the chuck to the spindle.

Take a block of wood and a hammer, put the wood block on the end of the chuck and tap it fairly hard with the hammer to lock it back on the spindle taper.

If the spindle isn't running out and your replace the chuck and it still runs out, replacement chucks are available at any box store, like Lowes or my usual sources, MSC, Production Tool or Enco.

I really doubt it's the spindle. Even the Chinese don't build that sloppy.

A Bridgeport is a bit of overkill for drilling and a cheap one will be beat to death anyway. I've rebuilt a few and replacement parts cost many times more than even a good drill press.

You can tell I like talking shop..........

 

[SidecarFlip]

A few years ago, I found a Dial Caliper at a garage sale. $20. The glass bezel was cracked and chipped. A machinest friend sent it to a place that repairs this kind of thing and had it cleaned, repaired and adjusted. Another $30. Total money spent was $50. for a Brown & Sharp caliper that will accurately read to .0001. I'm told it would be several hundred dollars to replace it today and the new one wouldn't be as good quality.

Moral of the story; Go with the wife to a yard sale/garage sale once in a while. One might be pleasantly surprised.

Starrett, Brown and Sharp, Fred Fowler and Mitituoyo are every bit as good today, if not better than they were 40 years ago (excepting Mititoyo because they weren't around 40 years ago).

They have all maintained excellent quality but the price is commensurate with the quality, in othjer words, not a cheap date. Like optics or fine guns....lol

Starrett and Brown and Sharp both offer rebuilding recalibrating services. I send in my machinist levels every few years to be recalibrated and reset to the master standard.

Any precision well made measuring tool, you only buy one time. I still have tools that I bought when I was in my apprentiship at 18. I'm 63. They are just as good and accurate as when I bought them.

Somebody is gonna make out like a bandit at my estate sale........

 

[Trickymissfit]

I doubt it's the spindle, .020-.030 is a lot. It's probably the drill chuck and thats replaceable. They are interference fit on the end of the spindle, which is tapered (usually a JT taper which is intrinsic to drill chucks).

The chuck might not be fully seated or seated crooked. It's easy to remove (the drill chuck). Take a cold chisel that will fit between the chuck and the end of the spindle and tap it with a hammer. The wedge of the chisel will remove the chuck. Then, you can check the taper to see if the spindle is running out that much (I doubt it is).

Inspect the taper hole in the chuck body and the taper on the spindle. Make sure there are no burrs on either mating parts, if there is, use some fine emery cloth to remove them, clean the bore and the spindle taper with a clean dry rag to remove any grit or oil and carefully re seat the chuck to the spindle.

Take a block of wood and a hammer, put the wood block on the end of the chuck and tap it fairly hard with the hammer to lock it back on the spindle taper.

If the spindle isn't running out and your replace the chuck and it still runs out, replacement chucks are available at any box store, like Lowes or my usual sources, MSC, Production Tool or Enco.

I really doubt it's the spindle. Even the Chinese don't build that sloppy.

A Bridgeport is a bit of overkill for drilling and a cheap one will be beat to death anyway. I've rebuilt a few and replacement parts cost many times more than even a good drill press.

You can tell I like talking shop..........

keep in mind that not all drill chucks are of the same quality!
* The best ones are the old Albrichts that carried a .0005" warranty. Jacobs and a couple others sold a copy, but never found one to be quite as good. These chucks are not made for heavy duty use, and at best for light work and small drill aps. They are rebuildable.

* the next best ones are the Jacobs ball bearing chucks. Once again these are rebuildable, and come without an arbor like the Albricht. This allows the end user to select what taper or bore size he wants to use with it. The jaws in these chucks as well as the Albrichts are soft, once you spin a drill in the chuck you usually have to rebuild them. Still for accuracey they are the very best.

* the rest are known as "plain bearing chucks", and they do not uses the ball bearing setup. Accuracey is not all that good with them, but still will usually be within .002"

Knowing that with a typical drill press the best you can expect is about .0015" TIR in a 12" circle, and .005" is not uncommon. I used to keep a new arbor that had the Morse taper on one end and the largest Jacobs taper on the other end. I'd install the bare arbor and set an indicator up to measure the run out in the taper. Anything more than about .0005" meant that there was a hiccup inside the bore.. Sometimes you can just polish it out with a wooden dowl and some sand paper. Other times I've had to take a round india stone and polish the bad place out. Becarefull here! Once the arbor is running fairly true you can then sweep the table top (run an india stone over the top to smooth it). Everybody has their own way of checking this, but I prefer to use something like a worn out Jo Block to measure off of. You just want something you know is parallel and maybe an 1/8" thick or even thicker. (a Parallel bar works very well) Once you got that done, reinstall the chuck and run the spindle at the lowest speed it will go. Then chuck up on the largest ground down pin you can put in the chuck. Measure the runout with the spindle running. Double the error, and that's about what you'll see with a reamer.

Also keep in mind that it's near impossible to drill a round hole! That's the real reason why we use reamers. There are three and four flute drills that are much better for getting a round hole, but nothing like a reamer will do. That's just the nature of the beast, and you need to know this upfront.
gary

 

[Trickymissfit]

Starrett, Brown and Sharp, Fred Fowler and Mitituoyo are every bit as good today, if not better than they were 40 years ago (excepting Mititoyo because they weren't around 40 years ago).

They have all maintained excellent quality but the price is commensurate with the quality, in othjer words, not a cheap date. Like optics or fine guns....lol

Starrett and Brown and Sharp both offer rebuilding recalibrating services. I send in my machinist levels every few years to be recalibrated and reset to the master standard.

Any precision well made measuring tool, you only buy one time. I still have tools that I bought when I was in my apprentiship at 18. I'm 63. They are just as good and accurate as when I bought them.

Somebody is gonna make out like a bandit at my estate sale........

most of the time I use a 4" pair of Mitutoyos that I bought in April 1970. Just as good today as they were new with the exception of some discoloring of the clear plastic cover on the dial.

When I retired I called down all my old apprentices (well I left two or three out). Gave two of them two sets of keys to the largest Snap On tool cart, and another. Told Mike that I'd pulled everything I wanted to keep, and the rest was theirs. The other box was full of combination wrenches all the way out to 2 1/2" in both inch and metric (I called them Viet Cong wrenches). There were two sets in each size, plus a 3/4" socket set that was complete. In the other box there were custom designed tools to fix machinery and build stuff. A couple dozen good dial indicators and just all sorts of odds and ends. Every once in awhile Mike will call me up about a machine he was sent out on that he knew I built. I'd tell him how to find the problem and then fix it.
gary

 

[SidecarFlip]

You mean Albrecht perhaps?

We have a few. A couple Rohm's but mostly Jacob ball bearing.

Sort of like making Dorian into drain.....

I'm not retired, well, sort of. I retired from the shop and opened my own shop. I was never one to take assignments well. Now I give assignments to my employees.

Never put much credence in hand tools like sockets and such. I've always considered Snap-On to be over priced. So long is it's an alloy (chrome vanadium) socket or wrench, properly heat treated and it's accurately broached and engages the fastener properly, that's good enough for me.

Precision tools are another matter entirely.

I don't fool with firearms either, except my own. Too much liability. I do external stuff for friends but thats it.

Finally, it is possible to have a twist drill cut a concentric hole, if it's jig ground but in real life it's not economically feasible. The reason a twist drill cuts an oval hole is the lands in respect to the cutting edges aren't equal.

For practical purposes machine ground drills suffice for 99% of hole applications.

Being as frugal as I am, I learned early on the offhand sharpening regimen so my drills get worn out because they get too short and I don't believe I have one non coated HSS drill in the shop and most are M42 Cobalt or micro-grain tungsten carbide.... we drill lots of high alloy and tool steel.

 

[Jinx-)]

I doubt it's the spindle, .020-.030 is a lot. It's probably the drill chuck and thats replaceable. They are interference fit on the end of the spindle, which is tapered (usually a JT taper which is intrinsic to drill chucks).
I really doubt it's the spindle. Even the Chinese don't build that sloppy.

Actually I measured spindle with chuck removed, I think it has to do with pulleys or how they are mounted to the spindle, also there were a lot of play with the quill, lowering it would shift another 50 thousands, so I couldn't get through 1/8 metal plate with 1/2 drill bit. Well I returned that drill press and bought Skil and for a drill press it runs true just 3 thousands off, which could be the chuck, but I don't bother, them 3 thousands are nothing when it comes to drilling.

 

[kc]

There are many who are new to this and have no idea why some tools are so important.

 

[SidecarFlip]

Actually I measured spindle with chuck removed, I think it has to do with pulleys or how they are mounted to the spindle, also there were a lot of play with the quill, lowering it would shift another 50 thousands, so I couldn't get through 1/8 metal plate with 1/2 drill bit. Well I returned that drill press and bought Skil and for a drill press it runs true just 3 thousands off, which could be the chuck, but I don't bother, them 3 thousands are nothing when it comes to drilling.

The accuracy (or lack of) in a spindle, on any machine tool, expensive or cheap, has everything to do with the bearings in the spindle housing, if, in fact, there are any (in a cheap machine). Bearing manufacturers rate beraings in classes of tolerance, with Class 5 being the tightest commercial rating and Class 1 being if it works, put it in. I lean toward Class 4-5 for general use and Class 5 for high precision like a surface grinder.

There are many who are new to this and have no idea why some tools are so important.

Very well put. Most times price will directly impact machine quality (just like scopes...lol). However, there are exceptions. I just haven't found any......

 

[Trickymissfit]

You mean Albrecht perhaps?

We have a few. A couple Rohm's but mostly Jacob ball bearing.

Sort of like making Dorian into drain.....

I'm not retired, well, sort of. I retired from the shop and opened my own shop. I was never one to take assignments well. Now I give assignments to my employees.

Never put much credence in hand tools like sockets and such. I've always considered Snap-On to be over priced. So long is it's an alloy (chrome vanadium) socket or wrench, properly heat treated and it's accurately broached and engages the fastener properly, that's good enough for me.

Precision tools are another matter entirely.

I don't fool with firearms either, except my own. Too much liability. I do external stuff for friends but thats it.

Finally, it is possible to have a twist drill cut a concentric hole, if it's jig ground but in real life it's not economically feasible. The reason a twist drill cuts an oval hole is the lands in respect to the cutting edges aren't equal.

For practical purposes machine ground drills suffice for 99% of hole applications.

Being as frugal as I am, I learned early on the offhand sharpening regimen so my drills get worn out because they get too short and I don't believe I have one non coated HSS drill in the shop and most are M42 Cobalt or micro-grain tungsten carbide.... we drill lots of high alloy and tool steel.

The average person will do well with something like a Craftsman set of tools, but if you make a living off your tools you look elsewhere. For hard use I like Williams better than anything else I've ever used, but have used about everybrand out there. I've also broke about every brand out there at one time or another. I use to own several torque multipliers, and if they say it's unbreakable; a multiplier will simply destroy it!

When I was young I worked with old Germans and master craftsmen. These guys could take a drill bit and sharpen it by had, and that drill would drill within five tenths everytime! With my eyes I was lucky to get three thousandths! So I just gave them to guys that did it for a living. On the otherhand I could make a threading tool that was near perfect everytime. Samething with a radius tool (always had trouble doing a female radius)

Somewhere I have a small tool box full of tool bits ground out of Rex 95. There's a complete set of radius bits all the way out to a half inch and just about everything else a guy could ever want to have. Then I have another box full of Vasco Supreme cutting tools. Plus the usual assortment of tool holders and inserts for tool blocks on a lathe. You accumulate a lot of stuff over 40+ plus years!

Back to round holes and a drill bit. Can't be done with a regular two flute drill. Maybe get close in some metals, but still not round. If you have access to a shadowgraph, drill a hole that's about 3/4" and have a good look at it. It will anywhere from three to six sided (maybe more). Now there is a way to take most of that out of small holes with a drill bit that is of high quality and only taking out about .003" a side. But is the hole has to take a lateral load it will give way premature. A reamed hole gives a much better bearing area and thus holds it size for a longer period. That's why most guys on jig bores simply drill a hole, and then bore it to size from there. A typical P&W or SIP will ream a hole withing a couple tenths everytime if the spindle line is good (as well as being properly aligned), but if the hole spec is tight you always use a boring head. I might add here that I had a set of over & under reamers in .0005" steps, and no one was allowed to touch them but me for a good reason! (a nominal holes size with a five tenth and one thousandth over and under reamer for each size out to one inch). Anything they couldn't do went to a Moore jig grinder or had the holes punch with a carbide ball
gary

 

[Trickymissfit]

The accuracy (or lack of) in a spindle, on any machine tool, expensive or cheap, has everything to do with the bearings in the spindle housing, if, in fact, there are any (in a cheap machine). Bearing manufacturers rate beraings in classes of tolerance, with Class 5 being the tightest commercial rating and Class 1 being if it works, put it in. I lean toward Class 4-5 for general use and Class 5 for high precision like a surface grinder.



Very well put. Most times price will directly impact machine quality (just like scopes...lol). However, there are exceptions. I just haven't found any......

actually that's incorrect. Bearings are rated by machined in error that is measured in runout. A tapered roller bearing (Timken) will be standard or have what is know as "O" quality. I think there is a double "O", but have not used one. Have used a lot of "O" grade bearings in spindle groups over the years. These things get pretty pricey, and after that they move into Hydra-Ribs and such, and these will buy you a lot of beer.

The most accurate bearings are known as ABEC 5/7/&9. There are still some a little better, but carry no specific ABEC number, and are used to grind ball bearings. In most spindle groups an ABEC 7 is standard. A high precision jig bore and many grinder heads will use ABEC 9's. There are some that use a different configuration of ball bearings that carry now specific rating (super precision ceramic bearing sets come to mind). Spindle lines are usually angular contact ball bearings with an O grade Timken to absord major thrust loads at times. As a rule the angular contact bearing sets (these are all matched to each other) is the stanadard setup. If the ball bearings have angular lines etched on the O.D. of the outter race it is known as an "MM" series ball bearing. These are usually ABEC 7's, but normally will test out as a minimum ABEC 9. The advantage with these is the bearing contact angle. Most are 25 degree, but some are as light as 12 degrees and some are as heavy as 35 degrees. The higher the number the heavier the longitudial load they'll handle. But by carring a heavier thrust load you give up run out. I never liked the 35 degree stuff, and most always used 17.5 and 25 degree bearings

A typical Bridgeport mill is shipped with ABEC 5 bearing in the quill, and the factory calls .001" good enough (per Bridgeport rep). By simply changing the bearing packs to ABEC 7's and puting the thrust under load you will increase the accuracey, but not a lot. Their spindles are not the greatest. I did rebuild one once that had .00025" compound error in 16". They're simply a weak design from the start.
gary

 

[SidecarFlip]

I use Williams myself, especially adjustable spanners. A little heads up..... The hand tools that Lowes sells, the Kobalt stuff in scokets and o.e. wrenches are Williams. I have no idea how that relationship transpired but it did and I take full advantage of it.

All my owned boring heads are Criterion, I have at least 5 in different configurations in Cat40, R8 and straight shank and I tend to use Kenmetal inserts and holders or Ascar but I hand grind toolbits for specific appliaction all the time.

You don't have to be German to be a good toolmaker, I know of some Irish toolmakers who are astute craftsmen.

You can buy the most sophisticated, accurate and expensive machine tools made but if you don't have the knowledge and skill to extract the full potential from them, they are a waste of time and money.

This is a fun thread for me......

Almost as much fun as going 'bang'....

 

[SidecarFlip]

actually that's incorrect. Bearings are rated by machined in error that is measured in runout. A tapered roller bearing (Timken) will be standard or have what is know as "O" quality. I think there is a double "O", but have not used one. Have used a lot of "O" grade bearings in spindle groups over the years. These things get pretty pricey, and after that they move into Hydra-Ribs and such, and these will buy you a lot of beer.

The most accurate bearings are known as ABEC 5/7/&9. There are still some a little better, but carry no specific ABEC number, and are used to grind ball bearings. In most spindle groups an ABEC 7 is standard. A high precision jig bore and many grinder heads will use ABEC 9's. There are some that use a different configuration of ball bearings that carry now specific rating (super precision ceramic bearing sets come to mind). Spindle lines are usually angular contact ball bearings with an O grade Timken to absord major thrust loads at times. As a rule the angular contact bearing sets (these are all matched to each other) is the stanadard setup. If the ball bearings have angular lines etched on the O.D. of the outter race it is known as an "MM" series ball bearing. These are usually ABEC 7's, but normally will test out as a minimum ABEC 9. The advantage with these is the bearing contact angle. Most are 25 degree, but some are as light as 12 degrees and some are as heavy as 35 degrees. The higher the number the heavier the longitudial load they'll handle. But by carring a heavier thrust load you give up run out. I never liked the 35 degree stuff, and most always used 17.5 and 25 degree bearings

A typical Bridgeport mill is shipped with ABEC 5 bearing in the quill, and the factory calls .001" good enough (per Bridgeport rep). By simply changing the bearing packs to ABEC 7's and puting the thrust under load you will increase the accuracey, but not a lot. Their spindles are not the greatest. I did rebuild one once that had .00025" compound error in 16". They're simply a weak design from the start.
gary

Gary..

As a rule I don't fool with a machines internals because I buy new unless it's an old beat up South Bend (which I restore and collect, quirky habit I guess).

When I need a bearing specifcation, I refer to my Detroit Ball catalog or Machinery's Handbook.

Buy new and maintain properly, as in proper lubrication and respectful employees.

I looked (after I read your post) and my toolroom grinder has 7 series bearings in the head. It's rated at 50 millionths plus or minus (in controlled ambient) but I've never achieved that (or want to). A tenth is close enough and most stuff in this shop is +- 0.001. The linear stuff is 0.005 in most cases.

In production runs, even short run production, there is a discernable line between profit and loss when it comes to accuracy. To coin an associates phrase...... 'Commercially Acceptable'

I'll respectfully disagree on your premise that the Bridgeport Mill is a weak design. Within it's capability parameters, it's a very good machine tool. If it wasn't, no one would have copied it and everyone did, some even copying the individual parts, like Lagun.......

 

[Trickymissfit]

Gary..

As a rule I don't fool with a machines internals because I buy new unless it's an old beat up South Bend (which I restore and collect, quirky habit I guess).

When I need a bearing specifcation, I refer to my Detroit Ball catalog or Machinery's Handbook.

Buy new and maintain properly, as in proper lubrication and respectful employees.

I looked (after I read your post) and my toolroom grinder has 7 series bearings in the head. It's rated at 50 millionths plus or minus (in controlled ambient) but I've never achieved that (or want to). A tenth is close enough and most stuff in this shop is +- 0.001. The linear stuff is 0.005 in most cases.

In production runs, even short run production, there is a discernable line between profit and loss when it comes to accuracy. To coin an associates phrase...... 'Commercially Acceptable'

I'll respectfully disagree on your premise that the Bridgeport Mill is a weak design. Within it's capability parameters, it's a very good machine tool. If it wasn't, no one would have copied it and everyone did, some even copying the individual parts, like Lagun.......

I know where your comming from, but even the Bridgeport reps will tell you that it's a weak design. The basic frame is pretty solid, but what they lack is a good spindle group design. Also the varible speed heads are well known for falling apart. There is a way to fix this issue, but you'll need access to a wire edm. Then there is the well known table issue (unless you use nothing but the 36" one). The machines most folks want are the longer ones, and I used to love them! The slide bearing surfaces are way too small for that kinda overhang, and tend to wear out quickly. The also transfers to the bottom of the saddle, causing premature wear. A Bridgeport has no serious lube system for the slides, and in most cases dosn't work anyway. If you fix it, it will drip oil all over the place. The next issue with a Bridgeport is the casting that the quill rides up and down in. It's prone to oblong wear, and really isn't finished well from the factory from the start. It's also an isse that's pretty nasty to fix, but can be done with a jig bore and some time. The quill itself leaves something to be desired with today's tooling. The R8 tool holder is probably better than the Bridgeport taper, but neither are anything to write home about. For ease of use the tapered tool hlder is better. Their draw bar system sucks when it's perfect! (always keep a spare draw bar on hand). The threads are too small, and really ought to be .50-20tpi. The spindle bearing pack is strong enough for .62" and smaller diameter end mills, and this is an area that needs a complete redesign. Then there is the lead screws that on a good day suck. That's why most folks that use theirs a lot goto scales.

Now being as we spoke of clones and such; let me tell you what a good clone looks like. The knee has removable hard steel ways. The samething for the saddle as well. The slides use Turcite running at .001" crush fit. The knee is also a little wider, and each set of ways are about 25% wider. The machine uses ball screws on every axis except for the vertical on the knee. The frame is of course slightly wider and is trussed inside to prevent any flex. Plus it supports a flood coolant system with the inside of the frame being the coolant tank. The quill is much larger in diameter with bigger bearings and a true thrust bearing setup. Tool holders are Ericson #40's with knob retention. The head is similar in style to a Bridgeport, but looks like it's on steriods. I can rebuild one of these machines for about 65% of the labor that a typical Bridgeport has in it. I might add here that the normal Bridgeport has not been made in America for a very long time, and the only thing they make over here are their CNC machine centers (also nothing to write home about) You can buy that machine for about 20% less than a Bridgeport with similar options. But even if you just have to have similar sized Bridgeport type machine, then at least look at the Southwest Trac. Not my favorite, but still better than a Bridgeport. (their lathes are junk)

Your probably looking at a #13 or a Taft Pierce grinder I assume. Both a very good grinders. A Taft Pierce with a Pope head is about as good as 99% of the people ever need. The best externals use hand scraped silver alloy bearings (never been inside the head on a Studer). A real pain to replace bearings in, but I've done more than my share. A typical Red Head comes with ABEC 9 ball bearings, and the best ones to use are from Barden. I have seen Red heads shipped with ABEC 7's, and with a phone call I learned that they were sold as roughing machines
gary

 

[SidecarFlip]

Guess I lucked out, both my mills are short table and refitted with ball screws and both have Kurt power drawbars. My take on a bridgeport is it's not a hogging machine and never was. They aren't rigid enough. If I want to hog, I have a Cincinatti horizontal mill. I'd have a K&T but they are too cumbersome. The Cincinatti is bad enough.

I'm careful with my slideways, they get oiled every morning with way oil in the one shot which works by the way and yes, the saddle drips oil but it's a mill, not a vase of flowers. The spindle oil cups are filled every morning too and both machines are step pulley. When one of my employees start a mill, I want to see an oil line across his shop apron.

I also have a Hass with conversational programming and Cat40 with through the spindle coolant. It runs primarily aluminum.

My favorite is my LeBlond Servo shift engine lathe. Always wanted a Monarch 10EE but I don't have time to rebuild one. Time consuming enough rebuilding old South Bend lathes and shapers. My last one took 3 years. The LeBlond line bored the spindle bearings on the last South Bend after I repoured them.

I'm just getting ready to purchase a 3 axis CNC Plasma table. I spend a bundle having parts cut. Besides, I want a new toy to play with and the bank says ok.

I'm really too old to be fooling with stuff that one, don't make money and two, take so much time because in the end, it ain't worth the time spent.... but I'm too stupid to retire I guess....

Yes, my toolroom grinder is on turcite ball ways.