New Pinion Gears

[ron_moorehead]

I just got new pinion gears for my ShopBot, the old gears were 30 teeth gears and the new ones are 25 teeth gears. I know I need to change the unit values in the software to match the new gears and I spent the last hours searching the forum trying to find the new values. Any ideas what the settings should be for the new 25 teeth gears? Thanks.

[Gary Campbell]

Ron...
A guess: {existing value} /30 *25 = new value

[knight_toolworks]

I thought the prt alpha uses the 20t? it could be 25 though. but the 30t is for the new upgraded motors shopbot offered while ago. they sent me those by accident and I did not have any torque at all.

[ron_moorehead]

By the way I have the 7.2 to 1 motors. Thanks.

[billp]

Ron,
I found this page on the Shopbot web page/Wiki. Hope it has your numbers;
http://shopbotwiki.com/index.php?title=PRTInchUnits

[richards]

For a non-Alpha machine, you can use this formula to compute the number of steps per inch:

1 / ( pinion gear pitch diameter * PI / Gear Ratio / Steps per Revolution) = Steps per Inch

For example:

A 25-tooth gear has a pitch diameter of 1.25 inches
PI = 3.1416
Assume a gear ratio of 3.6:1
Gecko stepper drivers have 10:1 micro stepping, so they require 2,000 steps per revolution

1 / ( 1.25 * 3.1416 / 3.6 / 2000 ) = 1833.461

That figure is very close to the value in the chart that Bill referred to. It's easier to look at the chart and find the value, but, to me at least, it's also good to know how the value was derived.

[gerryv]

Good to see you Mike. Hope the new year is bringing you improved health.

[gerryv]

Bill, A kind of dumb question no doubt but the chart does not mention Alpha units so I'm wondering if the Alpha's also use the 4g board or if they are a whole different kettle of fish? I've got a 2005 Alpha PRT and a 1st generation Buddy 32 standard and have often wondered. :o

[bob_dodd]

Ron On my Prs standard 4G 25 Tooth unit value for 3.6 is 1833.464 & for 7.2 is 3666.928 hope this helps

[billp]

Gerry,
Alphas ARE different animals than 4G machines ( Alpha drives on one, Gecko drives on the other...).
I posted the above source primarily as a "reminder" to people reading the Forum that many of the answers they are looking for CAN be found on the Shopbot Web page, Wiki, search engine ,etc. I am SURE that with a little digging the answer about Alphas can either be found online, OR from another Shopbotter with a similar configuration. Mike's (mercifully brief ) answer would be something people might want to keep a copy of just in case their internet connection was "questionable".
Of course an e-mail to tech support is always the safest bet if there is ANY question on someone's part about operating their machine to it's fullest capabilities...
Let's hope that the coming year is a great one for ALL !!!

[ron_moorehead]

Thanks guys for all the information.

I talked with ShopBot yesterday and got the right Unit Value for a Alpha with 7.2:1 motors and 25 teeth gear it is - 2979.3805 for future reference.

[ken_rychlik]

Ron, The z was 25 tooth on mine to begin with, so using that same value for the x and y should fix it if your z had the 25 tooth on it.