Re: Unimat 3 Milling Head
John,
I machined a new vertical column a few years ago to fit the DB200 with a triangular gib key. It allows vertical repositioning with absolute angular repeatability and it can be locked in position. I have a long threaded screw and hand crank for vertical movement. It works
similar to the ¡°UPLA¡± device that was sold on E-Bay a few year back.
Dick
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Hi Peter,
Some good ¡°rules of thumb¡± for designing with bolts.? These were bestowed on me over 35 years of mechanical design and product development from gifted and generous mentors.?
1. For steel bolts into mild or stainless steel, 1.5 diameters of thread will engage the full strength of the bolt threads. For example 1/4-20 ideally should have 3/8 min full thread.?
2. For blind holes, if possible you want an extra 1 diameter of tap drill depth to have room for chips to fall during tapping.?
3. For good steel you can go as little as 1 diameter for the thread strength but 1.5 allows for drilling pilot oversized. Research into thread strength has indicated that as little as 2-4 threads truly carry the full load of a bolt, but redundancy of 4-5 threads is a safe absolute minimum.? It takes into account thread yield and settling in of both bolt and nut threads.?
4. Aluminum bolts should not be considered structural bolts unless highly engineered , and anodized or hard coat anodized. Over time aluminum bolts oxidize and lose ductility. Aluminum bolts used anywhere need grease like lube. And yes over time an aluminum bolt and nut or thread joint will oxidize.?
5. For structural bolts into aluminum it takes 3 diameters of full threads to engage the full strength of a steel or stainless steel bolt. I have used both stainless and alloy steel in aluminum successfully. Best practice is to use grease on both. If you have ever seen aluminum car rims on a car after a few winters with road salt, the mating surfaces are always corroded and pitted and usually seized together from galvanic affect. Grease does help.?
Btw 18-8 or 304 stainless bolts are approx 40ksi yield and 80ksi ultimate strength. Socket head screws from unbrako or cam car or metric with stamped heads are usually approx 2x the strength of stainless.?
6. The failure in a bolted joint is always the bolt if it is pure tension. This is due to the small cross section of stress area. For this reason for steel in steel a fine threaded screw is always stronger than a course thread but assumes perfectly formed tapped hole. If the pilot drill drills over size you can quickly go from 75% engagement to 60 or 50 with just a couple number drill sizes. That is why most mechanical designers avoid fine threads in structural applications.? Also this allows you to pair high strength bolts with medium strength nuts because the nuts have properly formed threads.?
7. Important rule of thumb¡.if the screw looks too small, bump it up a size or 2.? Combined stresses in bolted joints can be considerable.?
8.? Minimum distance for a tapped hole or tight clearance hole for a bolt from the edge of a plate should be about 1 diameter. That is from center line of hole to edge. This engages full bolt strength and full clamping assuming the plate is approximately 1 diameter thick minimum. This usually eliminates plate hole tear out.?
9. It is easy to calculate tensile force or shear force in a joint and is tempting to use 1 bolt to do the job. Don¡¯t fall for this temptation in critical joints. Minimum of 2 bolts is better and 3 bolts is best as a minimum. This helps mitigate unplanned bending. There is an old saying that any bracket is a step. Don¡¯t want anyone getting hurt. Assume human body weight.?
10. Factors of safety. Any non-critical joint 1.5x.? Critical joints with shock loading 5x-8x factor of safety.? Overhead lifting 10x-12x FOS.?
Disclaimer: ?All above info is for reference only. Any critical fastener joint requires formal engineering. Just being conservative. ;)
Enjoy.?
On Mon, Aug 14, 2023 at 12:45 PM Dave Seiter < d.seiter@...> wrote:
Machinery's Handbook is a great source, but if you're going to get a used copy, newer editions will be better than older editions for metric info.? I have 4 or 5 editions, the oldest being from the 50's.? I've found that while most of the general info remains fairly constant throughout the years, more specialized data may require a little digging through multiple editions. I specifically remember needing a table of collet dimensions, which I'd seen before, and the book I grabbed did not have ANY data on collets.? (I think it was from the 90's). Newer and older editions did have the data.? If you're looking for information on old tech, like flat belt drive, really old editions would obviously be needed.?
-Dave
On Monday, August 14, 2023 at 03:52:22 AM PDT, Carl < carl.blum@...> wrote:
Hello Peter:
?
Machinery's Handbook also has Metric information, it will tell you USA measurements are based on the meter. Check Ebay or bookstores for a copy, even the early editions are useful. New they are about $100, but I've found used for $10. The book is a great read, everything from flooring to finance. It's size has stayed the same to fit in that small drawer in Girshner tool boxes.?
?
?
?
?
?
In tool making we always used stronger bolts. Aluminum would only be used for appearance or weight. Stainless bolts in stainless are prone to galling, this week I had a 1/4" screw gall in a stainless flange and I had to saw it free. I'm on the road with no grease so I used butter and finished the job.?
On 08/14/2023 2:45 AM EDT Peter Brooks < peter@...> wrote:
?
?
Thanks Bill. Is that an American book?? We are (for our sins) now?generally metric over here in the UK, I wonder if there is an equivalent?
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Re: Unimat 3 Milling Head
I¡¯m still getting used to using my U3 kit, so my comments are based on limited experience.
Mounted to the rear of the bed (by the two bolts) the milling attachment is pretty rigid and works well for milling, albeit within the usual Unimat limitations of size of cut.
I¡¯ve just been using it mounted to the slide with the single t-nut bolt that fits in the end of the milling column. This was to mill the sides of the hex head of a bolt using the dividing head. There was quite a bit of chatter and vibration using lateral movement, even taking very small cuts. In that configuration there are a lot more parts with the potential to move around.
There is a YouTube video I have seen of someone milling a ¡®way¡¯ into a U3 column (using a far bigger milling machine!), then using a grub screw through the cast body to optionally secure it. I¡¯ve been looking for someone who could do this. Otherwise repeatability when moving the column is an issue. My drill press could do with it as well!
I can¡¯t comment on the setting of angles at the head but I would imagine this could be tricky without some sort of geared arrangement for fine adjustment. Speaking of which the fine feed adjuster (for up and down movement) is vital, and works well with clear markings.
The U3 ¡®kit¡¯ is a certainly very clever and versatile machine. In the same spirit that people build up (say) classic Lotus Elans here in the UK using all the benefits of modern technology and hindsight (fully rust proofed spider chassis etc) I wonder how someone would or could build a U3 these days. A fairly pointless and fruitless task but an interesting thought.
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Re: Unimat 3 Milling Head
I have demoted the Fb1 mill to a drill press because the spindle is solid, so a cutter has more overhang and I don't have a fine feed attachment for the quill.? I bought an older Taig mill and mounted a Sherline head on it because Taig did not have an ER 16 spindle, and I liked the Sherline variable speed motor. Now Taig has a bigger motor on their mills and an ER 16 spindle.?? I like being able to stuff most of a double ended cutter up inside the spindle.?? The Taig column is a 2" square tube with a dovetail slide bolted on the front , so it makes a fairly stiff machine.?? I can run a 3/8" cutter on steel if I don't get too greedy with the depth of cut.
Chuck Daldry
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Re: Unimat 3 Milling Head
I have an Emco Fb1 mill.? That is a unimat 3 milling head and
column attached to a 3 1/2 " square x-y milling table.? The head
will tilt left and right, but not fore and aft.
Chuck Daldry
On 8/14/23 20:29, OldToolmaker via
groups.io wrote:
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I don¡¯t own a Unimat 3 but I have been looking at the Unimat 3
milling head and am intrigued by the adjustability and versatility
of the milling head. It sure seems to be able to be configured in
many ways. Is any one here able to comment on it¡¯s usefulness and
ease of use. It appears it might be somewhat of a challenge to set
the angles for compound milling. Comments?
Dick
--
forum/?OFF-SET-tailstock-center-65965#post105972
?SMALL TURRET TOOL POST
PLANS?
?LARGE TURRET TOOL POST PLANS
?MINI-LATHE CARRIAGE
LOCK PLANS
?SMALL QC TOOL POST PLANS?
?QUICK CHANGE LATHE TURRET
?MINI LATHE COMPOUND PIVOT
MODIFICATION
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Re: Unimat 3 Milling Head
If you do not already have a Uni 3, what are you proposing?? To buy the lathe and then the milling accessory?? The Uni 3 head, like the SL, has no guidance, so if you move it up/down, you lose everything.? So the only vertical motion is what you get from quill travel.? You also need the fine feed and of course a collet chuck.??
If you want a mill, buy the basic manual Sherline.? $723 + accessories.? If you want a little more, then Taig is under $1000.? Either have better milling capacity than Uni 3.
Now if you are outside the US, I do not know how you handle these.
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I don¡¯t own a Unimat 3 but I have been looking at the Unimat 3 milling head and am intrigued by the adjustability and versatility of the milling head. It sure seems to be able to be configured in many ways. Is any one here able to comment on it¡¯s usefulness and ease of use. It appears it might be somewhat of a challenge to set the angles for compound milling. Comments?
Dick
--
http://www.homemadetools.net/forum/?OFF-SET-tailstock-center-65965#post105972
?SMALL TURRET TOOL POST PLANS?
?LARGE TURRET TOOL POST PLANS
?MINI-LATHE CARRIAGE LOCK PLANS
?SMALL QC TOOL POST PLANS?
?QUICK CHANGE LATHE TURRET
?MINI LATHE COMPOUND PIVOT MODIFICATION
|
Machinery's Handbook is a great source, but if you're going to get a used copy, newer editions will be better than older editions for metric info.? I have 4 or 5 editions, the oldest being from the 50's.? I've found that while most of the general info remains fairly constant throughout the years, more specialized data may require a little digging through multiple editions. I specifically remember needing a table of collet dimensions, which I'd seen before, and the book I grabbed did not have ANY data on collets.? (I think it was from the 90's). Newer and older editions did have the data.? If you're looking for information on old tech, like flat belt drive, really old editions would obviously be needed.?
-Dave
On Monday, August 14, 2023 at 03:52:22 AM PDT, Carl <carl.blum@...> wrote:
Hello Peter:
?
Machinery's Handbook also has Metric information, it will tell you USA measurements are based on the meter. Check Ebay or bookstores for a copy, even the early editions are useful. New they are about $100, but I've found used for $10. The book is a great read, everything from flooring to finance. It's size has stayed the same to fit in that small drawer in Girshner tool boxes.?
?
?
?
?
?
In tool making we always used stronger bolts. Aluminum would only be used for appearance or weight. Stainless bolts in stainless are prone to galling, this week I had a 1/4" screw gall in a stainless flange and I had to saw it free. I'm on the road with no grease so I used butter and finished the job.?
On 08/14/2023 2:45 AM EDT Peter Brooks <peter@...> wrote:
?
?
Thanks Bill. Is that an American book? ?We are (for our sins) now?generally metric over here in the UK, I wonder if there is an equivalent?
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Re: Unimat Vertical Column
The DB etc is 25 mm by memory.
On 08/13/2023 2:26 PM EDT Peter Brooks <peter@...> wrote:
?
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Don¡¯t know about the DB200 but the U3 is around 28mm in diameter.
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I have worked on BSA, Triumph and Norton Motorcycles for 50+ years now. I have a large selection of the BSW, BSF taps dies and tools to work on these. You can also add the BA and the BSC threads to that lot. LOL, and when working on metric remember that Japan used their own Metric up until 1969, the JIS threads. And if you work on older American stuff you will also run into some interesting threads, like the Extra Extra fine and Special threads. Many decades ago when stuff was still made in the USA, we even had two special 1/4" extra fine threads for thin tubing. One was used for electric lamps and the other was for reostats where the shaft came out.? ?Very early American wrenches also used a system very close to the Whitworth where the wrench/spanner opening did not equal the hex head on the bolt , but was related to the shaft size. They also used a code on the wrench/spanner to signify the size of the opening and each manufacturer used their own code.The code was normally three numbers. Most of this stuff did not start to get standardized until after the SAE was formed 1905 and even then it was not until a few years more when the US supreme Court ruled that the Patent on the automobile did not include every nut and bolt that manufacturers started to standardize. Most consider WWII as the point where Nuts and bolts became more standard in sizing and threads. ?Here is a good link to dating tools.?
Jeff
On Monday, August 14, 2023 at 08:28:45 AM EDT, Keith S. Angus <keithsangus@...> wrote:
On Mon, Aug 14, 2023 at 06:40 AM, Peter Brooks wrote:
- is there a standard formula for the size (width and thickness) of bolt hex heads? ?(I¡¯m making some M14x1 bolts).
When Mr Whitworth devised his system of screw threads he made the hexagon twice the size of the thread across the points - not across the flats.?This means there is a factor of ¡Ì3 involved, so the AF size is never going to be rational in any system of measurement. This is why Whitworth size spanners never fit anything else, and I believe it is why the French and Italians (at least) refer to an adjustable spanner as an English spanner - it's the only thing that fits those daft British bolts! To add to the confusion British Standard Fine (BSF) bolts use the next size down hexagon. During the war this was then applied to Whitworth (BSW) bolts as well because it saved metal. The Whitworth formula for the size of a bolt head is still being taught in British drafting classes, and it is almost always wrong. Metric (SI) bolts do not use aa formula for the hex size. An M1 nut is 2.5 mm AF, M100 is 145 mm, so as the thread size goes up the nut is proportionately smaller. In general practice (my experience) M14s are 22 mm AF, but the latest ISO standards say 21 mm. I suggest you use 22 mm, then your standard 7/8 AF spanner will be a good fit. The metric nut thickness is roughly 0.8 of the thread size, but the numbers are rounded off to something a bit sensible. Bolt heads are 2/3 of the nominal size, again rounded off (M14 is 11 mm thick). So some of the metric dimensions follow a formula, but plenty don't. Beyond that there seems to be no limit to the imagination of engineers when devising "rational" fastener families.
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On Mon, Aug 14, 2023 at 11:52 AM, Carl wrote:
Stainless bolts in stainless are prone to galling,
Stainless bolts in anything are prone to galling. They are also nothing like as strong as the best high tensile steel. I only use them if it's absolutely necessary, as in the water filters I'm working on currently.
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On Mon, Aug 14, 2023 at 06:40 AM, Peter Brooks wrote:
- is there a standard formula for the size (width and thickness) of bolt hex heads? ?(I¡¯m making some M14x1 bolts).
When Mr Whitworth devised his system of screw threads he made the hexagon twice the size of the thread across the points - not across the flats.?This means there is a factor of ¡Ì3 involved, so the AF size is never going to be rational in any system of measurement. This is why Whitworth size spanners never fit anything else, and I believe it is why the French and Italians (at least) refer to an adjustable spanner as an English spanner - it's the only thing that fits those daft British bolts! To add to the confusion British Standard Fine (BSF) bolts use the next size down hexagon. During the war this was then applied to Whitworth (BSW) bolts as well because it saved metal. The Whitworth formula for the size of a bolt head is still being taught in British drafting classes, and it is almost always wrong. Metric (SI) bolts do not use aa formula for the hex size. An M1 nut is 2.5 mm AF, M100 is 145 mm, so as the thread size goes up the nut is proportionately smaller. In general practice (my experience) M14s are 22 mm AF, but the latest ISO standards say 21 mm. I suggest you use 22 mm, then your standard 7/8 AF spanner will be a good fit. The metric nut thickness is roughly 0.8 of the thread size, but the numbers are rounded off to something a bit sensible. Bolt heads are 2/3 of the nominal size, again rounded off (M14 is 11 mm thick). So some of the metric dimensions follow a formula, but plenty don't. Beyond that there seems to be no limit to the imagination of engineers when devising "rational" fastener families.
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That's great, thanks for the reply Carl.? Sounds like it's full of reading for the winter evenings...
Cute toolbox !
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Hello Peter:
?
Machinery's Handbook also has Metric information, it will tell you USA measurements are based on the meter. Check Ebay or bookstores for a copy, even the early editions are useful. New they are about $100, but I've found used for $10. The book is a great read, everything from flooring to finance. It's size has stayed the same to fit in that small drawer in Girshner tool boxes.?
?
?
?
?
?
In tool making we always used stronger bolts. Aluminum would only be used for appearance or weight. Stainless bolts in stainless are prone to galling, this week I had a 1/4" screw gall in a stainless flange and I had to saw it free. I'm on the road with no grease so I used butter and finished the job.?
On 08/14/2023 2:45 AM EDT Peter Brooks <peter@...> wrote:
?
?
Thanks Bill. Is that an American book? ?We are (for our sins) now?generally metric over here in the UK, I wonder if there is an equivalent?
|
Thanks Phil for that and the tip. I¡¯ll keep my eyes out for a copy.
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Hi Peter, we have the book (Engineers Bible) over here in the UK it's about 80mm thick so it has every bit of information you could need in it keep a look out for a copy.
On another note over the use of stainless bolts I use nothing else in many different metals and have done so for many years, but I always brush a film of copper grease on them and have never had any problems at all.
Phill?
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Thanks Bill. Is that an American book? ?We are (for our sins) now?generally metric over here in the UK, I wonder if there is an equivalent?
|
Lay hands on a copy of Machinery's Handbook, and you will find several hundreds of pages of tables, discussion, and formulae. I keep picking at it, but I'm mathematically challenged, and unlikely to live long enough to understand it all even if I live a hundred years longer. :)
Bill in OKC?
William R. Meyers, MSgt, USAF(Ret.)
Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement.? SEMPER GUMBY!
Expect in one hand, expectorate in the other. See which one gets full first.
On Monday, August 14, 2023 at 12:40:47 AM CDT, Peter Brooks <peter@...> wrote:
Some queries about bolts.
- common sense would say that a bolt should be softer than (or equal in hardness to) the thread that is is going in to, the bolt being replaceable where the threaded item is maybe not. If threading into aluminium there seems little option than to use an aluminium bolt but in the back of my mind I am highly suspicious of aluminium (like it might meld back together like the Terminator!). It¡¯s strange stuff. I¡¯ve heard that you shouldn¡¯t use stainless steel in aluminium (galvanic reaction apparently), are there any other combinations of metals that are unadvisable? ?I have anti-seize compounds, one copper based and another, from bicycle maintenance days, do folks use these in general engineering?
- is there a standard formula for the size (width and thickness) of bolt hex heads? ?(I¡¯m making some M14x1 bolts).
- given light loadings (we¡¯re not dangling stuff from cranes, or pulling supertankers) is there any difference in the strength of fixing between (say) a 10mm, a 20mm and a 30mm bolt? Is there any point to the length of a bolt apart from reaching down to a thread?
(I think this nearly qualifies for the ¡®Dumb questions¡¯ thread !)
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Some queries about bolts.
- common sense would say that a bolt should be softer than (or equal in hardness to) the thread that is is going in to, the bolt being replaceable where the threaded item is maybe not. If threading into aluminium there seems little option than to use an aluminium bolt but in the back of my mind I am highly suspicious of aluminium (like it might meld back together like the Terminator!). It¡¯s strange stuff. I¡¯ve heard that you shouldn¡¯t use stainless steel in aluminium (galvanic reaction apparently), are there any other combinations of metals that are unadvisable? ?I have anti-seize compounds, one copper based and another, from bicycle maintenance days, do folks use these in general engineering?
- is there a standard formula for the size (width and thickness) of bolt hex heads? ?(I¡¯m making some M14x1 bolts).
- given light loadings (we¡¯re not dangling stuff from cranes, or pulling supertankers) is there any difference in the strength of fixing between (say) a 10mm, a 20mm and a 30mm bolt? Is there any point to the length of a bolt apart from reaching down to a thread?
(I think this nearly qualifies for the ¡®Dumb questions¡¯ thread !)
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Re: Unimat Vertical Column
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On 14 Aug 2023, at 4:26 am, Peter Brooks <peter@...> wrote:
?Don¡¯t know about the DB200 but the U3 is around 28mm in diameter.
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OldToolmaker
Tool247
Carl
Bill in OKC too