[andypugh]

They look excellent Andy!

Is the 2nd photo a shot of the top of the drawbar? Are those 'keepers' - they look a lot like the widgets on top of engine-valves that keep the spring retainers on...

That's exactly what they are. From a Ford Puma Diesel (internal code-name for the Transit engine)

[H.O]

One thing I'd like to ask HO is just how critical it is to have the spindle taper hardened and ground?

Honestly, I don't know but I don't think I've come across a spindle that isn't hardened. Since the holders are hardened what will ware is the taper in the shaft. I felt (and feel) that the fabrication of the shaft with the bearingseats and their tolerances, the deep narrow bore for the drawbar tube, the taper and notches for the drivedogs makes the part complicated enough that I'd not want them to be "disposable" spare parts. Of course it depends on the actual design of the shaft.

Perhaps if you get some prehardened shafting that's still soft enough to be machined and fabricate it from that.

Having a shaft and then exchangable "noses" with the taper sounds very complicated and hard to get to run true etc.

/Henrik.

[digits]

Honestly, I don't know but I don't think I've come across a spindle that isn't hardened. Since the holders are hardened what will ware is the taper in the shaft. I felt (and feel) that the fabrication of the shaft with the bearingseats and their tolerances, the deep narrow bore for the drawbar tube, the taper and notches for the drivedogs makes the part complicated enough that I'd not want them to be "disposable" spare parts. Of course it depends on the actual design of the shaft.

Perhaps if you get some prehardened shafting that's still soft enough to be machined and fabricate it from that.

Having a shaft and then exchangable "noses" with the taper sounds very complicated and hard to get to run true etc.

/Henrik.

Cheers Henrik - I really wouldn't want to make all those parts of the spindle disposable either. What I had in mind was more like treating the taper like a lathe chuck/collet holder : the taper and drive dogs would be removable, and would fit inside the main spindle shaft with only ~0.5mm of clearance. They'd be bolted on the front of the spindle to allow you to true it up in-place.

[antsals]

Just been looking at the spindle build it looks really good. Has anyone come across anyone supplying ready built cartridge spindles? BT or HSK?

Cheers
Ant

[Adamj12b]

If you look on http://www.tormach.com/Product_PCNC_maint.html, about half way down there is a replacement bt-30 taper spindle cartridge.

-Adam

[andypugh]

As my drawbar is pretty much unrelated to the original thread, I have moved to this thread:
http://www.cnczone.com/forums/showpo...28&postcount=1

My drawbar is now working, and seems to hold the tools quite nicely.

[dwalsh62]

How do I know how much spring pressure I need for an ISO 20 tool holder, google yielded no real information.

It was suggested that 50lbs should be sufficient and others say 1000lbs, quite the discrepancy in values.

I don't believe 50lbs is sufficient and 1000lbs is way to much and google did not provide me with one anything useful.

I don't want tool slippage and I don't want overkill so if someone with an ISO 20/25 based system could tell me how much their machine has I would be thankful.

[H.O]

Hi,
I can't give you any "real" numbers for size 20 or 25 taper tools. What I did find when designing the spindle was that one manufacturer claimed 3900N while another 5500N for a size 30 taper. Going by those number I'm thinking that 1000lbs (which is ~4500N) is probably on the high side for a 20 taper but not entirly unreasonable.

I just Googled a bit and came up with this document from Schaublin where they claim 3000N for their ISO20 spindle and 4000N for their ISO25. So, there you go 1000lbs is probably right.

/Henrik.

[dwalsh62]

Hi,
I can't give you any "real" numbers for size 20 or 25 taper tools. What I did find when designing the spindle was that one manufacturer claimed 3900N while another 5500N for a size 30 taper. Going by those number I'm thinking that 1000lbs (which is ~4500N) is probably on the high side for a 20 taper but not entirly unreasonable.

I just Googled a bit and came up with this document from Schaublin where they claim 3000N for their ISO20 spindle and 4000N for their ISO25. So, there you go 1000lbs is probably right.

/Henrik.

Hmmm, got a chance to measure a Columbo spindle and it had 150lbs (650N) but is rated at 6000 - 18000 RPM which they say is a router type spindle and the lower weight will cause the tool holder to slip cutting aluminum at 4000 RPM.

I'm cutting mild steel at 2000 RPM so that is definitely insufficient.

The HAUS 20 has 425lbs (1900N) but rated at 2500 - 9000 RPM but is considered a lite-duty machine at 1.5HP spindle.

This is turning out to be more complicated that I expected.

My spindle is capable of 1000 - 18000 RPM and the lower speed is required for harder material so I have a dilemma, an air-cylinder capable of over 680lbs (3000N) is larger than the body of the spindle which is only 98mm x 88mm so how to achieve the desired results has become problematic.

[BillTodd]

...
My spindle is capable of 1000 - 18000 RPM and the lower speed is required for harder material so I have a dilemma, an air-cylinder capable of over 680lbs (3000N) is larger than the body of the spindle which is only 98mm x 88mm so how to achieve the desired results has become problematic.

How about making the spindle cylinder hydraulic, activated by an remote air cylinder?

[caf182]

I have a dilemma, an air-cylinder capable of over 680lbs (3000N) is larger than the body of the spindle which is only 98mm x 88mm so how to achieve the desired results has become problematic.

One solution is to use pneumatic cylinders that have a rod clean through them so that you can stack as many as you need.

Chris F
Soquel

[dwalsh62]

This issue has been solves, we worked it out with Frederico Possi from IMS S.A.S.

According to ISO specification, a low speed BT20 spindle (less than 5,000RPM) requires 680lbs while a high speed BT20 spindle (greater than 8,000RPM) requires 295lbs, no information was listed for a spindle with an RPM between 5,000 and 8,000 in BT20 size but since we want to cover a broad range we opted for the stronger listed force.

Using some modified off-the-shelf pneumatic cylinders with 15mm of travel we stacked 3 of them essentially giving us the force required while keeping the size at a minimum by using an extended body from a 50mm travel cylinder.

[eloid]

Is there a cad drawing available, I didnt read the complete thread
but want to know if a draw is a available?

great thread

[caferbur]

Hi, Greetings to all, great job, but where this phase, while no activity going HO.

[handlewanker]

Hi all. the original spindle build project has long gone, been sold off to someone else......it's now purely orientated to a gripper for ISO type tapers....IE 20 & 30 etc.

With the exact science of hindsight, it would have been better to have designed and made the spindle with an R8 type draw bar with QCT for TTS type parallel shank tools for the light mill originally in the first spindle build posts, but probably HO already had a number of ISO 30 tools so changing to parallel shank tools would not be on, even though when all else failed the spindle, with draw bar retainer which was the curse of the project, was sold off.

You can quite well imagine how in industry the design and R&D that goes into a machine is so vitally important if you want to get a working solution that actually works all the time.

One of the big problems with force is that you need materials that will withstand the effects of applying the force.....neglect the necessary criteria that apply and you can expect to crash and burn every time.

Having read all 154 posts on this thread very carefully, I have to come to the conclusion that very little original design went into the spindle and too much necessary design was totally lacking.

The fact that labyrinth sealing of the A/C bearings was totally forgotten in the initial design and subsequent build process is a glaring design fault, and as this is so very much a common necessity for spindle end problems where swarf, coolant and other foreign bodies are present, apart from the retention of lubricant, the spindle would have eventually failed from one of these factors.

Mention was made somewhere of a speed range in excess of 8,000 rpm........which is totally ludicrous in a DIY spindle build, for a lightly built mill, where design is totally absent.

I hope some lessons have been learned from the posts as if not, the same results will no doubt occur.

BTW, a relatively soft "spindle", that is using an unhardened Nickel Chrome steel, could have been made with a hardened insert with the necessary taper, Loctited in to solve all those problems that occurred.

One last point.....the top bearing needs to be a sealed radial type, axially floating in the housing, probably two together but only really necessary if the pull of the belt warrants it, as all the forces in this area are of a radial nature.

This will be one area where lubrication WILL be out of site and out of mind in design and thinking......in a spindle build for the purpose originally planned anything else would be totally ridiculous.
Ian.

[dwalsh62]

There was plenty of potential in this project and it died over time like so many spindle projects on CNCZone seem to do.

One of the guys from the group I share the CNC hobby with produces spindle shafts for HAAS so I have access to more information than most and help with the design of spindles which we have produced and sold and the current BT15 petal-clamp spindle design we are getting ready to put into production doesn't use labrynth seals but it does have environment protection and sealed bearings and is basically a scaled down version of the new HAAS BT40 spindle cartridge and later this year we will be producing a BT20 verison of this spindle.

Labrynth seals are not always used but sealing/environment protection is required and should be an important design consideration.

In the beginning, sealed AC bearings had life span issues but technology has come a long way in hybrid butyl seals that spindle manufacturers are taking another look at sealed bearings as a solution to lowering production costs without sacrificing life expectancy.

Some of the newer spindle designs that HAAS is using has sealed AC bearings and a felt o-ring/wiper for RPM's up to 15,000 but in the spirit of your comment, sealing/environment protection was not a design consideration and this is clear.

As far as BT30 goes, making a ball-clamp requiring special retention knobs with a short life span made no sense since petal clamps are available, significantly stronger and last significantly longer and if you have patience and time you can make one yourself from the known information for the retention knob and the generic petal clamp engineering notes for a given taper size.

In theory, the general design was a good concept but in my opinion the implementation was not the best execution, I can understand drawings hiding internal design details for a product that will be sold but, this project was to be openly available to anyone wanting to make their own so there shouldn't be any hiding going on which leads a sensible person to conclude that this is not what to do in a spindle design and hopefully the buyer has corrected the defects otherwise he will have serious warranty nightmares based on the design.

For those interested in checking out the BT15 spindle cartridge you can see it here.

[handlewanker]

Hi Dale, just checked out your spindle build and options on the Kickstarter project......now that is awesome.

I would have to think that with an RPM of 15,000 max, no one with only DIY skills can match that for any length of time.....cost not anticipated.

I think the build package around the $825 reward option has to be so tempting, you'll be oversubscribed in no time.

Just as a matter of interest, what would a spindle for ISO 30 (similar package as the ISO 15) run to on a Kickstarter program?
Ian.

[handlewanker]

Edit.....OOPS, double post.
Ian.

[dwalsh62]

Hi Dale, just checked out your spindle build and options on the Kickstarter project......now that is awesome.

I would have to think that with an RPM of 15,000 max, no one with only DIY skills can match that for any length of time.....cost not anticipated.

I think the build package around the $825 reward option has to be so tempting, you'll be oversubscribed in no time.

Just as a matter of interest, what would a spindle for ISO 30 (similar package as the ISO 15) run to on a Kickstarter program?
Ian.

As much as I would like to think I would be overrun, the majority of people are waiting to see if funding will succeed before committing to any purchase and they don't realize that at that time their chance to purchase at those (or cheaper) prices is gone.

if it doesn't fund and someone from our group has to shell out for the production run or you aren't a Kickstarter backer if it does fund, expect to pay more.

I already make a BT30 spindle cartridge, Servo Products is selling it, I sell it to them for around $1615.00 plus shipping (they buy more than one per order).

For ISO30, remove the nose blocks, make a stationary tool holder tray at the end of your table and you're up and running with ATC in no time.

[steve123]

Hi Dale, the ISO15 spindle looks very good, but I'm wondering if you can do more than engraving with it. The largest shank size is about 1/4" right? Can you talk about what kinds of work this spindle is good for? I'm not dissing your spindle, but trying to figure out where it fits.

I am a hobbyist, and am planning my first mill. I would use the spindle for some steel, but more aluminum, and some deep 3D work in wood (up to 6" deep). For some of it I think I would need at least a 1/2" shank. Would ISO20 be a better fit for me? The ISO15 is in budget, the ISO30 is not.

-Steve