How'd they get 44K rpm with 4 HP?

[DennisCNC]

Here are the links to the portable machine and hydraulic pump that powers it.
https://braxton-bragg.com/products/p...x_stone_cutter
https://braxton-bragg.com/products/p...hydraulic_unit

Wouldn't the power loss to push the oil eat up most of the HP? But it still has enough power that when two people push on the rouer it will not stall cutting 3CM granite.

Were else would high speed hydraulic motors like that be used?


Thanks

[skippy]

I'm not sure that they are high speed hydraulic motors as that would require re-inventing the wheel. The strong point of a hydraulic pump + motor unit is that they can transmit huge amounts of torque. For this reason it's my guess that they are using standard hydraulic components except that coupled to the motor (the driven piece) is a gearbox to increase the speed from motor speed (1 - 3k??) to tool speed (44k). Yes it's true that the torque would decrease inversely proportional (+/- 22x less) to the increase in speed (+/- 22x more) but in the case of hydraulics it transmits so much torque in the first place that even with a 22x reduction in torque "it still has enough power for two people to push on it without stalling".

[ger21]

Hey Phil, where 'ya been?

[skippy]

Hi Gerry (and everyone),
I've logged in here on the odd occasion over the last year but in general I've been out of action due to a major house renovation. My house is two story, long and narrow and it is built on solid rock. As I live on the coast, land is very expensive here so short of being a millionaire, the only way to have a house with a shed and live on the coast is to excavate downwards which is what I have done. I started with a basement of 4.8m wide x 4m long x 2.1m high. Now (much, much later) I have a basement that is +/-150m2 (1400sq/ft??) with 25cm thick concrete walls, 2.5m floor to ceiling height, heavy duty electrical installation, etc. I seem to recall seeing a post here called something like "what is your workshop like?". I intend to post some picies of my workshop there soon. Obviously this is all with the aim of getting my cnc activities going again. Some months ago I was talking with a mate of mine in Australia who decided to put up a shed behind his house. A week after making the decision the concreters arrived and laid the slab, 2 weeks later the prefab shed company people came and put it up in a day and a few days later the electrician did his bit and that was it. Totally painless unlike mine.
I haven't finished the house yet (about 4 months to go) and now it's almost August and no one here works in August (most if not all shops are shut) (mañana, mañana!). After that it's cnc time again! Sorry to hijack the thread.

[pedrocuello7]

Hi, I new in this CNC onine list , I've been a machinist for long time, I have experience working with universal mailling machine & especially lathes machine, so I 'd like to experience train my skill on those new programable CNC model . is there any online site that it can help on this issue ?

Regard, Pedro.

Thanks.

[DennisCNC]

Interesting thread.

Does any one have experiance runnning planetary gear boxes back wards?


Thanks

[skippy]

I too was thinking along the lines of a planetary setup but I can't imagine any normal planetary being able to handle a 44k input or in this case a 44k output. Turbines from the aircraft industry (aircraft APUs (auxilary power unit) and helicopters) have planetaries that operate at those speeds BUT of course they cost a fortune....
I'm stumped as to how they do it.

[dnl_grrr]

Originally Posted by DennisCNC Here are the links to the portable machine and hydraulic pump that powers it. https://braxton-bragg.com/products/p...x_stone_cutter https://braxton-bragg.com/products/p...hydraulic_unit Wouldn't the power loss to push the oil eat up most of the HP? But it still has enough power that when two people push on the rouer it will not stall cutting 3CM granite. Were else would high speed hydraulic motors like that be used? Thanks

having worked in the industrial automation industry for the past 25 years I have to say the stated rpm of 44,000 is a misprint just one too many zeros. rpm's of 4400 is more likely the case. a quick search of similarly priced saw blades yielded rpm's from 2400 thru 9300. as a ref. point gas turbine engines used to power electric generators operate at rpms 3000 thru 3600. opps gotta go

[skippy]

Maybe, but if I understand correctly this is a polisher using diamond tooling, not a saw blade (I can't get the page to come up at present to check that). Most diamond tooling in the stone industry (granite, etc.) runs at 30,000rpm upwards (correct me if I'm wrong stone guys) depending on tool diameter.
Re turbines, yes big ones run at low speed but small ones as in the case of certain turbochargers run regularly at 150k. It all depends on wheel diameter. But hey, all of this talk we're doing here is only supposition as to how they acheived 44k if, as you correctly ask, they in fact did achieve 44k at all.

[DennisCNC]

The only tooling that runs at high RPM is the diamond finger bits for trimming the edge and cutting out sinks or big ovals and curves on granite slabs the rest of the profiiling tools run around 5-8K. I don't need anything over 15K. I found another machine that uses a hydraulic head:
http://www.ghines.com/systar.html

This one is direct drive and goes up to 7k, I could live with that.
I emailed the company asking how much a replacement head will cost and a lady replied asking if I was going to use it to make something...DUH..of course
They probably had a few peps asking or something.

Do you think they are using a regular oil motor or is it something special?


Thanks

[dnl_grrr]

hydraulic oil

... guess I didnt read the description clearly

This hydraulically-powered machine uses a vertical
diamond cutter to: •Make free-hand cutouts •Drill pilot holes for faucets and cut sink holes (with Antarex Bit) •Follow templates in PVC or plywood to cut ornamental shapes •Make bas relief designs and

it seems to be the stone cutting equivilent to a "plunge router"

which reminds me of an air driven (turbine) router used to trim aircraft parts, the air assisted cooling the tool. it seems that electric motor driven units would overheat ruining the tool and part.

so... would a hydraulic turbine motor be possible, not like the low speed air turbine for air tools, but like a air driven turbine router, high flow/low torque.