Hi there all,,,help

[Oldman Prof]

I hope you all will be patient with me,as I said I am actually a welder by trade and know(I hope) most of the basics, I can do a few things and have made a few parts namely:work accurately enough to make a few firearm silencers that work well,slave cylinder for my SOHC 750 honda,brake reservoir for brake master cylinder on said honda 750 so I can work accurately.my problem comes in with my dividing head,my maths is worse that very bad so I try to use fixed formuli that I can find.I have a book on dividing,(will post pics) and the chart shown in it do not match up with the holes in my dividing plate,or rather say there are no charts for the holes I have in my plate and I was wondering if there is a formula to work this out for a dope like me
.
I'm looking at the highlighted "P" number of holes on the dividing plate to be used,not one of those holes in that column are on my plate so I need to know if that is a uncommon plate or am I just being an idiot and looking at the wrong thing,it is a 40:1 dividing head I have and I have made a chuck key for myself at(obviously) 10 turns per 1/4,let me know what other info anybody needs,sorry to seem so stupid but I probably am.PS: sorry the 37 row is there for 37 divisions and 148 divisions.

 

[chuckorlando]

Brother you aint stupid. I watched a class full of grown men get brain beat talking dividing heads with a really great instructor. What numbers are on the plates you have and what number are you trying to divide?

 

[Oldman Prof]

Well don't have a job for it at the moment, I just need to what can be divided,in other words is there a chart for that dividing plate,the holes are, 28,37,41,46,54,66. and only the 37 is on the chart in two places,37 divisions and 148 divisions. If I can't find a reference chart for the holes I have is there a formula I can use to work out any divisions I need,or reference chart for the plate I have,there is a picture of my one in my post.

 

[rgray]

Would be nice to have the other hole plates. You can divide even numbers that are on you're plate 28,46,54,66.... to do anything that requires 14,23,27,33... just double the number of holes moved since there are twice as many.

 

[DMS]

Here are the basics.

Lets say you want to divide a circle into 9 parts, you have a 1:40 dividing head and a plate with 54 holes.

Step 1: calculate the number of holes per 360 degrees. That is just the number of holes in the plate, multiplied by the ratio of the dividing head

54*40 = 2160

Step 2: Calculate the number of holes per index. Just divide the number of holes per 360 degrees by the total number of divisions.

2160/9 = 240

Step 3: Calculate the number of whole turns and partial turns per index

240/54 = 4.44

So, 4 full turns, plus a bit extra

54*4 = 216

216 is the number of holes we cover with full turns, subtract this from the number of holes per index to get the remainder (this will be the span of your sector arms)

240-216 = 24


The trick about the whole process is figuring out which plate to use. You want something that will divide out evenly with the number of divisions you want on the part. This stuff could be done pretty easily with a spreadsheet if you are so inclined.


Another example using the first entry in your table, 1:40, 21 divisions, 21 hole plate
40*21 = 840 (holes per 360 degrees)
840/21 = 40 (holes per index)
40/21 = 1.9 (turns per index)
1*21 = 21 (holes covered by full turns)
40-21 = 19 (remainder)

Which (thankfully), gives us the same result as your table, 1 turn + 19 holes.

 

[chuckorlando]

Maybe this will help out http://www.kinzers.com/don/MachineTools/EllisDivHead/EllisDividingChart.pdf

 

[Oldman Prof]

Thank you gentlemen,I see that it is an uncommon plate I have but I will have a go at the info you have supplied and see if I can come right.My problem from school days already is the calculating,I tend to see a number one way and after calculating,getting the wrong answer and checking sometimes 2-3 times,finding I've written for eg.214 instead of 241,the frustrating thing is I KNOW I do it and I still do it so I end up checking and re-checking and I've found it easier to work off standard charts,thanks for the info,I'm going to try to work out some simple dividing and get back to you,,looks like I will learn a lot here,,,,,,,Thank you again,

Anthony

 

[Bill Gruby]

What is the make of that Dividing Head Anthony?

"Billy G"

 

[stupoty]

Thank you gentlemen,I see that it is an uncommon plate I have but I will have a go at the info you have supplied and see if I can come right.My problem from school days already is the calculating,I tend to see a number one way and after calculating,getting the wrong answer and checking sometimes 2-3 times,finding I've written for eg.214 instead of 241,the frustrating thing is I KNOW I do it and I still do it so I end up checking and re-checking and I've found it easier to work off standard charts,thanks for the info,I'm going to try to work out some simple dividing and get back to you,,looks like I will learn a lot here,,,,,,,Thank you again,

Anthony

Have you tried the blue glasses? Apparently their good for reading dislexia, mine works the other way, it tends to come out in the wrong order.

Stuart

 

[Oldman Prof]

What is the make of that Dividing Head Anthony?

"Billy G"

I have no idea Billy,I got it with the Myford I had,never actually fitted anything and I had the base milled so I could drill holes to mount it to my present lathe,the only markings are the numbers on the plate and some numbers on the body.

Have you tried the blue glasses? Apparently their good for reading dislexia, mine works the other way, it tends to come out in the wrong order.

Stuart

Thanks Stupoty,
Maybe if I was still working I would try that but my glasses are damned expensive as it is(prisms and bi-focals) and I shudder to think what a blue tint would cost aswell,I'm 52 and I have a handle(mostly) on it,strangely reading is not a problem,only numbers WHILE I'm working out something,it's the reason I work off fixed charts and fumuli,it lessens my mistakes.I don't normally mention it because I have always (sometimes still) been told that I was lazy or stupid or both but I wholeheartedly appreciate all the help and advice I'm getting from you guy's,,,
Thank you
Anthony