How to Lay Out a Bolt Circle Without the Help of a DRO

hey guys it's Mike McMahan co machine and welcome back to the shop this week we have another how-to video how-to video this week is going to be about laying out a book whole circle on a piece of aluminum just using your machinist handbook and a couple tools out of your toolbox so the old man is pretty excited to show you about how he's been doing it for a while so I'm gonna take you guys over to the workbench and he's gonna go and show you guys how to do that hey guys welcome over to the bench Hey today I just want to kind of show you a little bit about how it's a layout a bolt circle which is common tools from usual box your machinery handbook we're gonna use a couple of scales pair of dividers we're going to use this pair of midotaur digital calipers you could use a standard pair you could use a pair of an ear calipers you could even use the the dividers again this is just common stuff found in your toolbox if you want to divide up a bolt circle if you're gonna drill it out on drill press maybe you have to drill it by hand maybe you need to lay out a bolt circle on a big piece of metal or a machine you're unable to use your digital readout on your mill if you want to do it this is a really simple way it doesn't require a lot of math I mean basically we're gonna be adding two numbers together here from our Machinery handbook so what we want to do today is we're gonna take a look at at the machinery handbook first so what I want to do is I want to lay out a we're gonna call this a this might be kind of hard for you to see but I'm gonna go and write it on here anyhow we're gonna do a 4 and 3/8 bolt circle and then I'm just gonna pick random over let's just do five holes okay it's the first thing I want to do here is I just want to give me a little center punch just kind of mark the center where this is going to be the center of my bolt circle next thing I want to do is I want to go ahead and lay out my bolt circle so we said it's going to be four and three eighths so we want to take half of the four and three eighths which is going to be two and three sixteenths so here's what we're going to do I normally like to start on the 1 so we need to set this up for two and three sixteenths which is going to make it three and three sixteenths on here okay see I started at the one move it in two and three sixteenths so this would give us half of our half of our bolt circle so we're gonna lay this out okay so the next thing we need to do is we're gonna locate our first hole if you were one to transfer a bolt circle on to a machine you really want to know where your first hole needs to be clocked at on this piece you get this piece to fit on there right but for this exercise it really doesn't matter so I'm just going to take and just mark a random spot it's kind of critical that you get your Center punch in the center of your bolt circle line okay so that's gonna be my first hole that'll be hole number one so I'm just gonna mark that that's gonna be our first hole so now the next thing we need to do is we need to get out our machinery handbook so I've got a couple copies of the machinery handbook I got a fifteenth I've got a seventeenth I've got a couple newer ones so I think I've got probably three copies four copies of this book by far this is my favorite one and it may just be a sentimental reason this book was given to me by a gentleman that was in World War 2 who's that actually drove a landing craft that brought troops ashore during World War two after World War two he decided to become a machinist and then I was lucky enough to know him when I was in high school and then got my first machinist job he actually lived up the street from us and him and my father were friends so I was able to to get some of his tools he was retired by that time so he had he had the machinery handbook he had a button indicator set I think there was some small small hole gauges I don't know there was a box of tools that he basically gave me he wanted me to have so this book you know kind of means a lot to me so I've used it a lot through the years you can see how dirty it is but it says this is still my go-to book so I've kind of marked the pages here where we need to be at but I'm just gonna go to them and kind of show you what we would look up you'll see the pages are dirty I mean again I've used this book a lot over the years so we got we looked up circles so then we want the length of cords for dividing so we're gonna we want the length of the cord going around the outer dime that circle to get us our five holes so the length of courts for dividing is on page 74 75 to 78 that's up in the front of the book so the very first page gives us a number of spaces and the cord length and you can do a multiplication factor here depending on how many spaces you want with this length of this cord and it'll give you your both your your your cords for your circles what we're gonna use we're going to use this next chart here this is the one that's kind of my go-to one here so we've got number of divisions we're going to go down to five and then we're going to go over to three-eighths and that's going to give us point two to zero so we want to write that number down or punch that into the calculator then we're gonna come down here to the bottom half of the page number of divisions again is five our bolt circle we said was four so four and three eight so we already got the three eights so then we need to add two point three five one and we're going to add that to the point two two zero okay so we're gonna set the machinery handbook aside so we're going to add those two numbers together so we're going to add the point two two zero plus 0.25 0.0 0.5 seven one that's going to give us two point seven I did that math room you check that again two point two zero plus two point three five one yeah that's more like it two point five seven one so that's the length of our cord so I'm just gonna write that on here two point five seven one this is cord length all right so we're gonna sit calculate inside for this exercise I'm gonna use these digital calipers I really don't use these calipers hardly ever at all I it's not that I don't like them I've just I'd like to dial calipers a lot I've always used dial calipers but this is a good set of calipers here so it'll be good for this exercise so we'll run this out to 2.57 one seven one there we go look what Snug this down so again we got our cord length so then all we're gonna do is I've got a set of tramble points too since this is just aluminum I'm not worried about you know we're not gonna mess up this para caliper so I'm just gonna step these off the pair of calipers just kind of show you I could get the tramble points out to you but we won't do that this time so here I'm just going to start stepping this off and alls I'm doing is putting the point in the end of the last cord with any luck this will divide this up pretty close episode we're real close there maybe off just a touch not very much though so again these are gonna be our holes so we got one hole two three four five so that was the leave our cord was this this arc so do you want to go through there and you'd want to you know excuse your Center punch and go through and Center punch all these that's where I see a lot of new people that I've helped out over the years you know layout bolt circles are kind of show them how to do this is they rush through this this part of it they've done all the work and get it all laid out real nice and then when it comes to put the center punch on the on the two cross hatches here they get it off one way or the other and then when they go to drill their hole they're both circles off just a little bit so take your time put it on there I normally like to lay it over on its side get the point right on it and then bring it up to it and then pop it so again that's just my personal preference I hope this little short video just kind of helped you out a little bit here again this is something really simple it's just they'll be able to lay out a bolt circle now I could drill this by hand or I could drill this in the drill press I don't need a digital readout on a milling machine or on a drill press to be able to lay out a nice bolts or clear and if you noticed in the book whenever we were looking at it those those couple pages there you really don't even have to do too much math you just basically got to add a couple numbers together so we could have picked any number of divisions here it goes up to 32 and over to 14 and it's it's in sixteenths up here and then the next couple pages here give you a little bit of the mathematical tables but for simplicity sake if you're gonna lay out a bold circle that's that's in sixteenths and up to 14 inches you use these two pages as long as you don't have more than 32 divisions you add your two numbers together and you get your bolt circle again we used digital calipers pair of dividers center punch ruler you could have laid out the cord with the the cord with the this the calipers as well you know you could have set this on here this goes up to 64 she could have got real close to that number just by using the pair of calipers so again I think this is just a nice easy way to do it I thought this would be a good exercise to kind of show everybody we had a little job in the shop not too long ago where we had to lay out a bold circle on a on a side of a of a piece for a farm implement so I kind of did that did it by hand on there and I thought maybe that was something neat we could show everybody it's just something you can do with simple tools you have in your toolbox you don't need to spend a lot of money pair of calipers you could use veneer calipers you could use dividers and a couple of rules and lay this out and get your your bold circle so I hope this little video was hopeful I'm gonna send you back over to Mike and thanks for watching hey guys I hope you guys enjoyed that short hop to segment they're laying off that bull whole circle using nothing but your machinist handbook and a couple tools out of your toolbox you just can't beat it all before I in this video I want to mention though we're getting really close to our 2016 with the channel you guys have heard me say this a couple times you guys that are new to the channel though when we hit that 2000 mark we got a small buff batch of tools then we're gonna be giving away we're actually gonna good showcase that for you guys in our next video next video is going to be a tool talk video about some stuff that we picked up in the shop a couple stuff that we purchased off the internet and then we have a local stores around us that sell use machinery stuff that we picked up from those guys as well so we get to showcase that to you guys in our next video other than that guys make sure you keep hitting that subscribe button keep hitting those like bugs and if you guys haven't already hit that little ding button next to subscribe button and it'll let you guys know we'll get our next video up so you guys can't miss the giveaway oh and that guys keep making chips and I'll see you next time

Channel: Mamco Machining

Views: 8,467

Keywords: mamco, mamco machining inc, mike campbell, home machine shop, back yard shop, how to video, small machine shop, owning a small shop, how to start your small shop, help, bolt hole circle, layout circle, manual, how to lay out a bc with calipers., how to scribe a bolt hole circle, with little to no math, machinist hand book, how to make perfect

Id: x23rS9nKGdI

Length: 13min 1sec (781 seconds)

Published: Tue Feb 19 2019