# Is This Possible On A Mill?



## Izzy (Oct 8, 2016)

Alright guys so I've got a part i need to make but up until recently I haven't had any sort of machinery so ive been paying people to make parts for me... Well now ive got a Bridgeport and was wondering if it where possible to make this part on the ole mill? I understand it would be a million times easier on a lathe but I don't have one I don't think it's possible but I figured I would give it go and farm out the question. Demnsions are as follows...
44mm I.d.
55mm o.d.
300mm of m55x2.0 external threads
15mm of m48x1.5 internal threads,
A snap ring Grove
Wrench slots
The part is 335mm in length


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## JimDawson (Oct 8, 2016)

Possible?  Yes.  Practical, I don't think so.  It is possible to use a rotary table and gear it to the X feed to cut the external threads, or a 4 axis CNC mill would do it.  Given the cost of tooling up to do this, you would be better to buy a lathe.


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## Izzy (Oct 8, 2016)

Yea I figures it would be difficult if at all possible, here's the thing I just bought the machine not to long ago and i want to get tooled up anyways, I wana get some boring bars, reamers, fly cutters etc... What all would I need to do this? And how i go about the setup?


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## Izzy (Oct 8, 2016)

the travel on my machine is:
X- 30"
Y- 16"
Z- 15"


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## JimDawson (Oct 8, 2016)

The basic setup to cut the external threads on a manual mill would look something like this:




This is showing cutting a worm gear, but the principal is the same.  Threading is just a spiral around a cylinder with a specific profile.

To make that part you would need a boring head and bars to bore for the internal thread,  then a tap to cut the threads.  It's possible to mill the threads with a thread mill, but you would have to gear the Z axis to a rotary table or spacer similar to the setup above.

Here is my super spacer



The snap ring groove could be milled with a tiny end mill or a slitting saw.  The OD could be ''turned'' using setup similar to the above, but I have never been satisfied with the result when trying that.


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## Wreck™Wreck (Oct 8, 2016)

JimDawson said:


> Possible?  Yes.  Practical, I don't think so.  It is possible to use a rotary table and gear it to the X feed to cut the external threads, or a 4 axis CNC mill would do it.  Given the cost of tooling up to do this, you would be better to buy a lathe.


Just about anything is possible given time and money, that would be a formidable part using an old manual Bridgeport knee mill, one will have built a machine to make one part very slowly at great expense.


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## Izzy (Oct 8, 2016)

thats pretty neat, so it looks like a dividing head with gearing to one of the X-axis hand wheels if im correct? also it looks like thats how you would go about cutting a helical gear for say a ring gear of a differential? if thats the case ive already been looking into dividing heads ill need them for other projects like cutting gears and custom sized hubs for my racecar anyways and ive always been the type of person to make due with what i have! dont get me wrong i understand a lathe would be much easier but the fact is i dont have one and i plan on buying alot of these tools for my mill anyways. does the gearing fixture have a name?


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## TOOLMASTER (Oct 8, 2016)

I would stick to having someone else do it...


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## JimDawson (Oct 8, 2016)

Izzy said:


> so it looks like a dividing head with gearing to one of the X-axis hand wheels if im correct?



That is correct.  It is _possible_ to cut any kind of gearing you want on a mill, but I have no experience with it.  



Izzy said:


> does the gearing fixture have a name?



I'm sure it does, but I don't know what it is.  ''Gear train'' maybe?  It really hasn't been done this way in many years, at least not in any kind of production setting.  It would be possible to design and build your own gear train components, including the gears.  Theoretically it could all be done on a mill.  It would be quite a job and take some time, but it could be done.  I have a 4 axis CNC mill, but it's not a job I would tackle, just not cost effective.  Spur gears can be bought for reasonable prices.


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## Izzy (Oct 8, 2016)

the only kind of machine i have access too is the mill and im by no means a production shop ive been building this car for over 3 years so how long it will take to produce this is not a factor. anything i can learn and do myself i would much much rather do it like that than simply pay someone else to do it. theres just something about having my own personal knowledge on how to do things appeals to me. not to mention not everyone is made of money i make very little, i paid more for one of these tubes than i did for my entire machine with tooling! i have a nak for finding things ridiculously cheap, i just need to know what to look for. as for the gears you think my best bet would be to get a dividing head and buy my own gears and make my own fixture for it? is there somewhere id be bale to get more info on that process? trust me i would much rather do this on a lathe but i dont have that kinda money right now....


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## Wreck™Wreck (Oct 8, 2016)

Your goal of producing internal and external threads on a mill is possible in most every way, this will require a serious amount of gear train building on your end.

Let everyone how it works for you.


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## JimDawson (Oct 8, 2016)

I'm not going to say it would be impossible to find a dividing head and all of the change gears to drive it from the lead screw.  But finding that might be difficult.  Many dividing heads are set up to be able to attach a gear train to them, and even those that aren't would be possible to adapt.  With a dividing head you could make your own spur gears for the gear train.  You just need to buy the proper involute gear cutters, or you can single point them with a tool holder that is something like a straight fly cutter and use hand shaped tool bits.

To cut the m55x2.0 external threads for instance, you'll need a 60° V-cutter and you'll need to move the table 2mm for each revolution of the part.  What gearing it takes to get there is just math.  Many dividing heads have a 40:1 ratio, your lead screw has a lead of 0.200 inch (5.08 mm) per revolution.  So you need to turn the lead screw 0.3937 turns for each 40 turns of the dividing head drive.  So If I did the math correctly  that gives you a ratio of 0.00984:1 or 101.6:1 depending on which way you look at it.  So then it's a matter of making a set of change gears that will give you that ratio.  Since gears are integers, finding the right combination is just a mathematical excersize.

I think I see a Machinery's Handbook in your future.

Another way to do this using modern technology is to put stepper motors on both the lead screw and the dividing head drive and use electronic gearing.  That would save many many hours of making gears and is relatively inexpensive.  Much less than buying gears.


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## Izzy (Oct 8, 2016)

Thanks alot Jim! That's the exact kinda info I'm looking for! And I deffinetly plan on getting myself a handbook at some point Im guessing all that info is in there? What about hobbing? Is that another option ooorrr?? Sorry for the super basic questions I'm just starting out the whole machining thing


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## JimDawson (Oct 8, 2016)

Hobbing is a possibility, in that case you would have to drive the dividing head from the spindle because the hob and the work have to be synced.  Electronic gearing here is far easier to set up on a BP mill because there is no easy way to mechanically transmit power from aa BP head to any accessory device unless you bought a horizontal head attachment and drove the dividing head from that shaft some way.  I don't ever remember seeing that done.


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## John Hasler (Oct 8, 2016)

Izzy said:


> i have a nak for finding things ridiculously cheap


Your best bet would be to put that knack to work finding a cheap lathe.   I got one that could make your part for $500.


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## Izzy (Oct 8, 2016)

Unfortunately my knack has failed me on this one can't really find anything that cheap, but the guy I bought the machine off of has a dividing head and a few plates to go with it tail stock an all for a couple hundred and a bunch of other tooling for really cheap because he's retiring... no lathes tho :/ I would like to get a lathe at some point but it's hard to find anything under a grand around here  I was honestly lucky to get this machine as cheap as I did!


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## John Hasler (Oct 8, 2016)

Izzy said:


> Unfortunately my knack has failed me on this one can't really find anything that cheap, but the guy I bought the machine off of has a dividing head and a few plates to go with it tail stock an all for a couple hundred and a bunch of other tooling for really cheap because he's retiring... no lathes tho :/ I would like to get a lathe at some point but it's hard to find anything under a grand around here  I was honestly lucky to get this machine as cheap as I did!


Ok.  Motorize your dividing head and couple the drive to the table X direction through an appropriate gear ratio.  Put a 60 degree cutter in the spindle and you've got a live-tooling lathe that can thread.


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## DaveInMi (Oct 9, 2016)

I sold my last lathe for $400 and it would have done that job.  It had some wear but one can usually work around that if practicality is your main goal.  My experience has been that tooling is more costly than the machinery.


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## rgray (Oct 9, 2016)

Is that a shock body?


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## Izzy (Oct 9, 2016)

John Hasler said:


> Ok.  Motorize your dividing head and couple the drive to the table X direction through an appropriate gear ratio.  Put a 60 degree cutter in the spindle and you've got a live-tooling lathe that can thread.


Thanks! I've been doing a bit of homework and I came across this really neat setup that basically converts a vertical mill to a horizontal mill, you basically move the turret out so the spindle is waay past the work piece then theres the fixture that bolts up to the dovetail underneath the turret then using a right angle head and arbor that connects to the fixture and bam horizontal mill! I also seen some setups of the diving head ran off the table via pulleys and a belt



DaveInMi said:


> I sold my last lathe for $400 and it would have done that job.  It had some wear but one can usually work around that if practicality is your main goal.  My experience has been that tooling is more costly than the machinery.


You're also in the states, 400 USD is almost 600cad things around here are stupid expensive, infact  Ontario has some of the highest living expenses in the world! Hydro for example costs 115$ if you have your entire house shut off for the month cuz that's just the delivery fee! Gas is at about 4.50 a gallon.... I do alot of my shopping in the states because of this! 


rgray said:


> Is that a shock body?


 yes sir it is! Its a custom made strut tube for some custom built coilovers I've been working on for a while


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## 4GSR (Oct 9, 2016)

One thing to remember, even if you could set up and cut the thread on the mill, the Bridgeport mill more than likely has a 5 pitch english leadscrew on it.  It would need to be a metric leadscrew in order to cut metric threads.  Be the same issue on a lathe, too.  As for using transposing gears on the mill to cut metric pitches, never heard of anyone doing it, but anything is possible.  A programmable fourth axis would be the way to go on a mill.  Ken


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## Izzy (Oct 9, 2016)

Well I appreciate the input it definitely gives me something to think about, one thing I should mention is its a series 2 standard I don't know if the lead screw on that is any different from the series 1 tho. If anyone has any links on the process I'm really interested In learning! I found this link that kind of explains what I was thinking about but I would need to tilt my head close to 90°! https://johnfsworkshop.org/home/mak...-helical-gears-on-a-vertical-milling-machine/  I'm gonna look into the whole cnc programing thing and 4th axis thing and see if that's something I could do...


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## Reeltor (Oct 9, 2016)

It seems like the direction of the thread is to mill the threads using a dividing head.  Since the OP will now be in the market for a dividing head, be sure that the dividing head is a Universal Dividing Head and not "Semi-universal"  The universal dividing head will have a tail off the rear end that attaches to the drive train and the table.
The cost of a good universal dividing head plus the gearing to connect to the table plus the attachment for the gears to attach to the table and the list goes on...  would be more than what a nice used lathe would cost.
Attached is a page from a VanNorman accessories brochure showing the VN 10" dividing head.  I think that all Van Norman dividing heads are the universal style.  In the used (and New) market the semi-universal style dividing head is much more common than a universal.  Also, a universal dividing head must match the mill.
While I think that collecting tooling for your mill is a great idea; I have my doubts about the practically of using the mill to cut your threads.  
I have never found a used universal dividing head with all the attachments necessary to connect the travel of the table with the rotation of the dividing head.  Seems like all the necessary bits and pieces get separated from each other.

Maybe someone can machine your metric threads for you on their lathe?  What about a tap and die?


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## Izzy (Oct 9, 2016)

I didn't think they made taps and dies that big! I would need a specialized handle to drive the dies tho wouldn't I? I'm honestly open to ideas on how to get this done. Gearing would be tricky as the dividing head would have to spin relatively quickly in relation to the X-axis movement. And no matter which way I slice it I'd like to tool up my mill and get a lathe but I can't do both. cheapest lathe I can find around here is about 2k. I have a line on a universal brown and sharp dividing head with plates and tail stock he only wants 250 for that and an older Kurt milling vice, I don't have a vice yet either so that's a pretty good deal I think. I may end up just paying to have the other 2 made for me  unless someone knows someone around the Ontario area with a cheap lathe id like it to be at least 15" in-between chuck and tail stock.


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## rgray (Oct 9, 2016)

Izzy said:


> I have a line on a universal brown and sharp dividing head with plates and tail stock he only wants 250 for that and an older Kurt milling vice



Sounds like a deal. Might want to snap that up. Even if you never use it for the shock body.


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## Reeltor (Oct 9, 2016)

That is a really great price for a dividing head and a Kurt vise, don't let it get away from you.  Check out Keith Rucker of Vintage Machinery . org on YouTube.  He showed the tear-down and clean-up of a BS style dividing head


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## John Hasler (Oct 9, 2016)

Izzy said:


> I didn't think they made taps and dies that big! I would need a specialized handle to drive the dies tho wouldn't I?


https://www.amazon.com/Metric-Right-Thread-2-0mm-Pitch/dp/B009QHNJ6U

You'd need to fabricate a jig for it as well as a fixture for the part but that wouldn't be too hard.


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## 4GSR (Oct 9, 2016)

Man, I used to have a B & S universal dividing head with most of the gears and the mill I used it on, too.  It's long gone.

I think before I dumped $$$$ into all of this tooling, I think a good lathe would fit the bill and give you much less headaches getting it to work for you.  I realize you have the mill, but to get it set up to make that part is going to be an expensive investment compared to buying a lathe setup ready to go.  Just my honest opinion. Ken


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## Izzy (Oct 9, 2016)

Like I said I would love to have a lathe but I honestly can't find one that suits my needs for any less than 2k but I have a line on cheap tooling for this mill because of the guy retiring, he's got one of those metal shipping containers filled to the ceiling with tooling for this mill that he's almost giving away with what he's asking for them


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## JimDawson (Oct 9, 2016)

That being the case, I would be over there buying whatever you can afford.  The Kurt vise and B&S dividing head sound like a screaming deal.  You might also take your shock tube with you and ask him how he would do it on your mill since there is a chance that he may have the tooling in the container.


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## Izzy (Oct 9, 2016)

That's the plan! Me and him got a deal worked out. For anyone wondering I got the machine for 300cad which works out to be just over 225usd. I only make like 1600 a month and rent is 1050 plus all my bills I really don't have alot of money to play with so he's been really good to me as far as pricing goes


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## Izzy (Oct 13, 2016)

So I've been doing a little research on thread milling and I'm thinking this actually may be possible and for alot easier than I've been going about it. Still using a dividing head I found this setup it cuts 1.5mm threads with a little modification it could do 2.0mm threads 



  ive also seen people use a rotory table and electric motor and the part spins at a set rpm and table feed is set to a specific feed rate to cut the threads anyone heard of this or have more info on this? I have enough travel on all 3 axes to do this so I can position the part standing or laying down parallel or perpendicular to the table


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## John Hasler (Oct 13, 2016)

Here's a blue-sky approach: secure a 2mm nut inside the part, secure a piece of matching 2mm allthread horizonally above the table, and then drive the part onto the allthead so that it passes under the cutter in the spindle.  You'll need a bushing secured to the table on each side of the cutter to stabilize the part and a handwheel of some sort on the part to turn it with (The table doesn't move, of course).


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## Izzy (Oct 13, 2016)

That is absolutely genius!!! That sounds one hell of alot easier than how I'm thinking about doing it! I'll have to explore this option!


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## JimDawson (Oct 13, 2016)

Izzy said:


> ...........ive also seen people use a rotory table and electric motor and the part spins at a set rpm and table feed is set to a specific feed rate to cut the threads anyone heard of this or have more info on this?



That's what I was talking about above, it's called electronic gearing.  There a few ways to do it, but the easiest and cheapest way to do it today is to use stepper motors and just drive it with Mach3.  This also gives you the option of cutting any thread you want just by changing a couple of numbers.


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## Izzy (Oct 13, 2016)

Oooh ok I get what your saying i've never heard of mach3 tho I'll have to do some research  and learn more about that.


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## JimDawson (Oct 13, 2016)

Mach3 is probably the most common CNC software used by hobbyists, 10's of thousands of users.

That,  a computer,  and a kit like this is about all you need
http://www.ebay.com/itm/USAFREE-2Ax...073160?hash=item4af7914708:g:E4IAAOSwCypWnd0Q


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## Izzy (Oct 14, 2016)

I was just about to ask if I'd have to convert my machine to cnc but that answers that! What about the knee could I put that on cnc control aswell?


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## JimDawson (Oct 14, 2016)

Well, kinda   What I am suggesting above is more of a partial CNC for one specific task.  It just replaces gears or chains & sprockets.  A full on CNC is not a bad idea.

Yes you could add control to the knee, but the more common method is to add it to the quill.  But having a powered knee sure saves a lot of cranking.  I love mine.  Mine is only powered, but not under computer control.


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## Chipper5783 (Oct 14, 2016)

Wow, fascinating thread.  What you are wanting to do is sometimes referred to as spiral, or helical, milling.  As others have pointed out, 4 axis CNC provides a way of performing this – “thread milling” – which I have never done.  With such a long component, it may present a challenge with tool overhang.


The picture you showed and much of the discussion is around conventional, manual spiral milling – which I have done, once.  That is quite a fine thread to attempt by mechanical thread milling.  For example the coarsest “thread” I would be able to mill is 8 tpi – using the standard gear set for my machine.  The coarser of the threads you are looking at is between 12 & 13 tpi.  I appreciate that what you want is a metric thread, but that can be converted using a 127 tooth gear (and add to the gear set to go beyond what it was intended for).  There are probably numerous ways that the different manufacturer’s have configured their offerings – on my machine the short lead selections (less than 3” lead in one turn), is that the dividing head is turned by hand, which feeds back through the end gears to move the table.  For longer leads (greater than 3”) the table is fed (hand or power) and the dividing head get turned by the gearing from the lead screw.


I get it that you have the opportunity to purchase all sorts of tooling for that mill you have, and you should seriously buy as much as you can afford.  However, I would caution you against getting set up for spiral milling.  There are many other milling machine operations that would typically be more common / useful than setting up for spiral milling.  Typically spiral milling jobs would be “once in a blue moon”.  Since you indicated you are tight on cash, I suggest you share what tooling you have the opportunity to purchase and a list of jobs you hope to undertake and the people in this community would be glad to recommend what would generally build that mill into a widely versatile machine.


As you said in your first post (and numerous others have agreed) – what you want to do, would be way easier on a lathe.  You said you had seen lathe(s) in your area starting at about $2000 (and you would need to add some for tooling, depending on what it came with) would be less expensive than most of what you have been considering to make that part with out a lathe.  The people who have replied that what you want to do is “possible” are correct.  I agree it is possible, but wow.  Certainly it would depend on what opportunities you are able to track down – buy cheap, fix, repurpose etc.  However, if you are going from scratch that is a serious undertaking.  One consideration I have not seen anyone share is that you could use your mill to make a “lathe like” machine.  More like a threading bench than a lathe.  Perhaps a thread chasing set up instead of end gears, lead screw etc.


I have never seen any active machining set ups (i.e. home hobby shops) with just a milling machine.  I have seen numerous with just a lathe and various small support machines – that works well (that is all I had for many years).  Perhaps others here could comment on the versatility of mill only work shops?

Attached are pictures of my one spiral milling job, recutting the ramps on a Reeves drive (mechanical variable speed pulley).


Let us know how you make out?


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## JimDawson (Oct 14, 2016)

Good advice Chipper!   Your Maho is an interesting machine, don't think I have ever seen one like it.


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## Izzy (Oct 14, 2016)

@Chipper I never planned on having a mill only shop and I would really love to have a lathe I just happen to find a needle in hay stack kind of deal which allowed me to get a mill. The only tooling I have for this mill is a couple face cutters and a couple 2&3 flute end mills. I'm a mechanic by trade so ive got all the tools your general mechanic would have, wrenches, ratchets, pullers taps, dies etc...


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