Jointer rpm again revisited (OD verses pitch diamter)

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I am confused over readin soem of the responses to my previous posting on pulleys and rpm speed. When calculating, do I use od of pulley or something else? All I have is the od for each pulley.

My plan was to use a 5 inch pulley on the 1740 rpm motor and a 2 inch pulley on the jointer. Using the od numbers, this gives me a rpm of

4350. Right?

The manual for this old jointer says to shoot for a cutter head speed of 4400.

BUT

It says with a 3450 rpm motor, a 2.5 inch motor pulley would equal the appreopriate rpm. (It does not say what pulley came stock on the jointer. When I got it from an auction it had a 2.5 inch pulley on the jointer but I have no way of knowing if that is stock or not.

After reading what someone said about pitch diameter being different than od, will I be spinning this thing too fast? Am I even supposed to go buy pitch diameter?

Any help is appreciated! I also have a 6 inch pulley and the 2.5 inch pulley. (Spares)

Reply to
stryped
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Yes. Any decent pulley table will list the pitch diameters with at least a couple of belt form factors. Look in the MSC or McMaster catalogs. One (or both) of them have it in the Browning section.

LLoyd

Reply to
Lloyd E. Sponenburgh

x-no-archive:yes

So I am spinning too fast? What pulley combo should I be using with what I have?

I do not have those catalogs by the way.

All the book says is to shoot for 4400 cutter head speed. Lloyd E. Sp>

Reply to
stryped

Stryped, I'm DONE. You're doing this troll shit again where every single answer you get, you say you can't do that, or can't find it, or can't understand it. By a freaking book! The damn catalogs are on-freaking-line! You don't want help, you just want to abuse the people helping you.

LLoyd

Reply to
Lloyd E. Sponenburgh

================== There are several diameters....

These include the actual physical OD or "outside diameter" of the pulley that you can directly measure, and the PD or "pitch diameter" that you cannot.

When calculating step-up/step-down ratios you need to use the PDs and not the ODs. The PD is more-or-less where the center of the belt rides and is somewhat less than the physical OD, the exact value depending on the cross/section of the belt.

Most pulley catalog listings will include the PD information as well as the physical OD information. When you look up the PD value for your existing pulleys, be sure to use values from the same belt size/cross section pulleys, as these are different for different belt sizes with the same physical OD.

Another machining "gotcha."

Unka George (George McDuffee)

I sincerely believe . . . banking establishments are more dangerous than standing armies, and that the principle of spending money to be paid by posterity, under the name of funding, is but swindling futurity on a large scale. Thomas Jefferson (1743?1826), U.S. president. Letter, 28 May 1816, to political philosopher and Senator John Taylor

Reply to
F. George McDuffee

Hi Lloyd

It is interesting that there are so many guys in this news group who are so ready and willing to help guys like this. Maybe he actually serves a purpose. His posts allow the experienced guys to voice their knowledge. Maybe those helpful posts will help some other reader. I have read Stryped's posts (to this and other news groups) that are so off topic that they are actually laughable/funny. Yet, he gets the helpful guys to respond.

Jerry

Reply to
Jerry Martes

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