How do you check the speed of a lathe?

[regalghost]

Hi

Just wondering how you check the speed of a lathe?

Thanks

[macca2]

Hi Ghost, welcome to the forum.
I don't know the answer to your question, but I guess you have to start with the speed of the motor and then work out the lathe speed depending on the size of the pulleys.

cheers macca

[Barry_White]

Hi Ghost

Welcome also.

With the Jet Mini Lathe it has plate showing the RPM for the given pulley setting. Don't know about bigger Jets but possibly so if it is on one type I would think they would put it on all their models.

[Sebastiaan56]

The fun way would be with a variable speed strobe, $15 from Jaycar if you want to make one, http://www.jaycar.com.au/productView.asp?ID=KJ8206&CATID=&keywords=strobe&SPECIAL=&form=KEYWORD&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=

Probably the easiest way would be to refer to the manufacturers manual for the lathe,

Sebastiaan

[tanii51]

this is how i do it ..... motor speed x diameter of motor pulley then divided by work pulley diameter doesnt matter what units you use ...eg inches cms... mm as long as they are the same.

eg motor speed 1440rpm
motor pulley diam 10cm( or 4 inches)
work pulley diam 5 cm( 2 inches)

1440x10/5 =2880

[speedy]

this is how i do it ..... motor speed x diameter of motor pulley then divided by work pulley diameter doesnt matter what units you use ...eg inches cms... mm as long as they are the same.

eg motor speed 1440rpm
motor pulley diam 10cm( or 4 inches)
work pulley diam 5 cm( 2 inches)

1440x10/5 =2880


That looks about right to me.:D

[regalghost]

Thanks For All The Help
Have Got What I Needed Thanks Once Again

[BANNED]

Hi regalghost
I've got a better suggestion, that I don't believe is known by most turners.

I already got the timber moister metter, which works a treat, and I got the RPM metter coming. I thing this is a must tool to have, insted of trying to work out the rpm from a graph. Anyway lathe RPM varies, depending on some circumbstances, with the size of the peace been turn a factor, and are other. You find that 90% of times the RPM showing on the lathe factory plate, are higher then what the simple turns.

This eBay seller, is ok and he sends the items very quickly, mine was a week from the US.

Have a look at his site for more info.
http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=220138201739&ih=012&category=1504&ssPageName=STORE:PROMOBOX:NEWLIST#LIST
Cheers
GV

[DavidG]

I just look at what the display says as I turn the knob. :;

[OGYT]

I'd like to have a digital tach, but the formula is close enough for me.

Not tryin' to hijack the thread, but what is this 1440 rpm motor?
The usual motors that I see here in the upover are: 2 speed - 1140 & 1725. Single speed motors are normally 1725 or 3350.
Is 1440 a normal speed of motors manufactured in Oz? I noticed that the VS Vicmarc VL100 comes with a 1/3hp, 1440 rpm, 240 volt motor. Is 220-240 volt electricity the normal household voltage in Oz?
Just curious.

[joe greiner]

Is 220-240 volt electricity the normal household voltage in Oz?
Just curious.

Yes. Also 50Hz. That's one of the reasons very little power tools export from Oosa to Oz. Observe, too, that 1725 x 5/6 = 1438, or 1440 with rounding.

Joe

[OGYT]

Joe, "what's the 1725 X 5/6 = 1438" mean? You tryin' to tell me that their 1440rpm motor turns the same rpm as our 1725rpm motor? I always thought rpms is rpms.... :U
....Just dense, I guess.

[Solutions Aust]

Hi

Just wondering how you check the speed of a lathe?

Thanks

Looks like you have received sufficient formula to now check what your spindle speeds are.
My question is now that you have the speeds, what are you going to do with them.

Cheers
Woodfast Aust:rolleyes:

[rsser]

Isn't the more critical factor the speed of the piece at the point you're taking shavings?

So you need rpm x circumference?

Other simple way is run it so fast it vibrates too much or you feel you need a continence pad to continue ... then back off :U

Added: btw, welcome regalhost.

[Gra]

Mount up a square blank, switch on the lathe and stick in your finger.

Count the OW!'s for one minute, then divide by four...


Skew was thinking that but wasn't willing to say it

[Skew ChiDAMN!!]

Skew was thinking that but wasn't willing to say it

Dang! Gotta be quick. :p

I tend to agree with Ern, crank it up and then back off 'til you feel safe. This works well for small to medium sized items (say, under 8" dia) although it can lead to explosive revelations for larger pieces which haven't been thoroughly checked for flaws, checks, etc.

(All ahead, adrenaline factor 8! K'Pla!)

[rsser]

Square blank, peg and piece of card on tool rest, then count ;-} Easier on Medicare.

Old joke: city slicker goes bushwalking on the Bogong High Plains. Mob of cattle grazing there ... (when this was how we treated alpine ecosystems), stockman on horse looking over them. City boy asks: 'Gee, how many cows you got there?' Working man takes a quick look across and says '296'. City boy observes 'Wow, you count quick'. Working man (prob. by name of Lovick) replies 'Nah, just count the legs and divide by four mate'.
.

[wheelinround]

Hi regalghost
I've got a better suggestion, that I don't believe is known by most turners.

I already got the timber moister metter, which works a treat, and I got the RPM metter coming. I thing this is a must tool to have, insted of trying to work out the rpm from a graph. Anyway lathe RPM varies, depending on some circumbstances, with the size of the peace been turn a factor, and are other. You find that 90% of times the RPM showing on the lathe factory plate, are higher then what the simple turns.

This eBay seller, is ok and he sends the items very quickly, mine was a week from the US.

Have a look at his site for more info.
http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=220138201739&ih=012&category=1504&ssPageName=STORE:PROMOBOX:NEWLIST#LIST
Cheers
GV

Nice piece of equip not a bad price either to check and see if lathe is doing what it's supposed to RPM, could show if motor or variable speed is correct and bearings not binding etc.

[Calm]

Only beng a newbie to this but i dont think that RPM are relevant. regardless of the size of the peice of wood the RPM is the same. Ern was spot on it is speed or MPh or KPH or feet per minute that is relevant. That way regardless of how far you are from the centre you need the wood turning at the right speed so the tools work at their optimum. Calculating that is going to be a huge exercise so i suggest ern's method. Screw up the speed until your boots start shakin and hld on.


- How's that for a detailed bit of crap??????????????

[theyoungster]

this might be of some help
http://cgi.ebay.com.au/New-Digital-Photo-Tachometer-Tool-for-Metal-Wood-Lathe_W0QQitemZ220138235312QQihZ012QQcategoryZ105805QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

bryce

[hughie]

To save all the who-hah of working it out, try this link. Just feed your details in and it will give speeds,belt lengths etc.



http://www.csgnetwork.com/pulleybeltcalc.html (http://www.csgnetwork.com/pulleybeltcalc.html)

[joe greiner]

Joe, "what's the 1725 X 5/6 = 1438" mean? You tryin' to tell me that their 1440rpm motor turns the same rpm as our 1725rpm motor?

Not quite, Al. A motor wired for 1725rpm at 60Hz would turn at 1440 on 50Hz. So I'd guess the wiring's the same, if not the same motor.

David, you're exactly right. But rpm is the only thing we can control, and usually the only feedback on machines so equipped. A surface speedometer might be perfect, but you'd have to move it around to different radii. If you consult tables of recommended rpm's for various diameters, [and calculate surface speeds], you get a more or less consistent range. Isn't that amazing?:wink:

Joe