Match an Existing Bolt Hole Pattern (BHP)

[@michaellitzkow8123]

Nice video - thanks Lee. For those wondering how to remember the formula 2 years from now when you need it, you can find it in Machinery's Handbook. It's in the chapter on Math in the section on Geometry in the subsection on Regular Polygons in a sub-subsection called Formulas for Circular Segments. That happens to be page 77 in the 29'th edition, but the page number will vary in other editions. Also note that the formula in Machinery's Handbook is for the radius of the circle while Lee's formula is for the diameter.

[@arfonjones7188]

Otherwise, the (unknown) radius, half the distance between the holes and the excluded angle defined by 360 degrees divided by the number of holes and then halved again gives the right angled triangle to which the trig function can be applied. So here, the pitch circle diameter equals the distance between the holes divided by sine(360/(5*2)).

[@jameslezak7882]

Great video Lee! I ran machines for years that had dro's but no other function but location. One didn't even have absolute function. When dro's started getting all the functions I'd already moved on to NC machines. When I got my machines for my home shop I bit the bullet and installed the best dro's I could buy on my mill and lathe. Pricey but makes my hobby so much more enjoyable. Great tutorial on using one of the dro features. Even though I know how to do many of the things you video I still watch, because your ways of explaining your process is so good! I use many of your examples when showing my kids and now grand kids how to do things. Some people are better teachers than others! Thanks for your time and sharing, Lee! 👍😎✌️

[@aviatorblc]

Wow !!! What a lifesaver!! I'm currently a new CAD greenie, and I have to make a dxf drawing from a vintage 1934 Bugatti Type 57 Stelvia steering wheel. IT has a hole in the center for the horn button surrounded by six bolt holes. You have just pointed me down the right road to get that bolt-hole pattern correct. Thank you SO MUCH.

[@TheFalconJetDriver]

I really appreciate that you showed the steps to input the numbers into the calculator!🛫😁

[@jimpritz4169]

Great explanation Lee. I also would like to see the caliper explanation. Thank you.

[@gregwmanning]

Yes please for manual BHP. Thanks for these videos

[@taranson3057]

I’m a mathtard when it comes to stuff like this, but your explanation was very helpful, in all honesty I can use all the helpful hints that I can get.

[@shipsofscale]

I just found your video. I really like watching and listening to you. I wish my father had your skills.

[@dankrzeminski6370]

Nothing is perfect, just a degree of accuracy lol, great video my friend.

[@OkieRCguy]

You had me at math! I appreciate you sharing the formula with us uninitiated

[@johnbowhill3080]

Thankyou Lee, l found this both entertaining, and very informative. Thanks again

[@jayminor9757]

It’s only perfect but it will have to do. Thanks for the great review on BCDs with the DRO. First time I ever used mine on my Precision Mathew’s mill I was ecstatic with the results. I had to match a bolt pattern on a fly wheel on a small marine diesel to make a holding fixture to remove the attachment hardware the fit was perfect and it was so easy after determining the diameter .

[@BTimmer]

Please do more on the manual way of doing a hole pattern. This one was very informative but I don't have a DRO.

[@rok1475]

Another method is to draw a shape (pentagon in this case) in any CAD program with a side the equals hole distance. Measure in CAD the distance from center to any vertex and you are done. It is quicker than typing numbers into the calculator. As a bonus you can print the pattern then glue it to material and drill decent hole pattern on a drill press.

[@danfreitas7905]

Yes, for those of us that do not have a mill. Please layout the bolt hole pattern using a pair of dividers.

[@michaelrosenlof1084]

As always, excellent presentation of very helpful techniques-Thank you very much ✅👍

[@wallbawden5511]

Lee any information you wish to pass along is fine with me good refresher on the bolt hole on the D R O so a paper lay out one would come in handy as well thanks great videos all of them have done a catch up on them all thanks Lee

[@Scottforyoutube]

Great video! I have learned a lot from your channel! I'm new to the hobby and you have helped me trendously! Thanks!

[@wilsont6651]

Great video. Its not often that I learn something about my Iphone while I am watching a machining video. Great explanation of the trig involved in determining the diameter of the bolt hole pattern. Thanks for taking the time to make the video.

[@krisnewman3202]

Thank you for this video Lee, I appreciate your clearly stated presentation. The DRO lesson was also much appreciated and I would welcome your suggestion of a video about a non-DRO layout.

[@terry42481]

I would like to see it. I would also like to learn more about the DRO's functions. You do a good job explaining in terms I understand. God Bliss!

[@terryheimerl8674]

Lee, I grew up using copper sulphate as marking dye and a good lathe was one that didn't have chipped teeth on the lead screw. I enjoyed watching your video and look forward to watching others. Terry from Australia.

[@goptools]

Hi Lee, I don't have a mill but do occasionally need to make a bolt hole pattern. This is helpful. Also, I know you showed it last week too, but showing how to get the scientific functions for the cell phone calculator, was great tip. Very simple but something I did not know. Thanks for the video! -mike

[@Richard-nb4iv]

Great video! I thought this would be much more complicated to learn, but you explained it clearly and made it look easy. Thank you. I would like to see a video using the calipers. That's the way I would have to do it. 👍

[@musicmaneman38]

I like the change gear wall. Never thought about that one. Thanks for the visual tip.

[@wland8549]

Hey Lee, Your channel name speaks for itself. Subbed.

[@1OlBull]

Lee, Very good explanation. I have a dro on my mill, but haven't used the bolt hole pattern feature in quite a while. Great refresher...

[@MatterLabz]

Very helpful guide. Thanks for sharing this procedure. New subscriber.

[@jamiebuckley1769]

exelent video lee really enjoyed it and learned what i was always wondering on how to layout bolt holes. yes and please show how to layout bolt holes with dividers that would be very good to know. thumbs up. i have a dro on my 9x49 atrump mill.

[@DS-Turbo]

Love these instructional videos

[@AmateurRedneckWorkshop]

Thanks for the trig lesson every little bit of knowledge is very valuable. So you noticed I had my zero angle on the other end of the mill bed. That comes with a story. When I got my mill it arrived with a broken "X" axis dro scale. The fine folks at Precison Matthews had a new one shipped from China. This took about 3 weeks and when I got it I forgot which way it was mounted and put it on backwards. This worked just fine anyway and I did not discover it until I was trying to make a radius with the dro. Strangely the left curve went right and the right curve went left and they were upside down. This gave me a clue that the "X" scale was backwards. Slow thinker that I am it took me a few days to figure that out. Now my zero angle is on the same side as yours and all of the radius formulas work as planned. Keep on keeping on.

[@MrPragmaticLee]

Try a test piece and see if you set your Starting Angle at 0 and Ending Angle at 360. I used to subtract from 360 for my ending angle but found it wasn’t necessary. Also, glad you got your scale on properly. 😉 The direction can be reversed in some DROs, but like you found, that setting must match the scale install direction. Thanks for stopping by.

[@AmateurRedneckWorkshop]

@@MrPragmaticLee I was too lazy to take the scale off I just reversed it in the DRO. Yeah I have entered the end point both ways. I always do a dry run to see if the holes are an in the right spot before I cut some metal. I like to use artificial metal. 😉

[@brucemansfield2501]

I'd like to see the other method for laying out a bhp.

[@donaldnaymon3270]

Great video. Excellent instructions. Thank you for sharing.

[@arfonjones7188]

A quick quality control check of the bolt pattern of a hub would be, using calipers , to measure the distance of each bolt hole to the edge of the large centre hub hole and then the distance between each bolt hole, sequentially. . Not as an absolute, but as a comparator within a defined tolerance. Just as a check to see how 'perfect' the existing bolt hole pattern is.

[@pauljcampbell2997]

That was really helpful. Thank you Sir!

[@Okie-Tom]

I always enjoy your videos. Thank you. Tom

[@jeffanderson4979]

Thank you for the simple explanation

[@Just1GuyMetalworks]

Great video 😊. Very well explained and executed 👍😁👍.

[@alleznape]

Great vid but I do have a question. In your formula you had written bolt hole center distance but you appeared to be measuring the edge to edge distance with your dig calipers. Was there something you did to compensate for that? Am I missing something?

[@MrPragmaticLee]

I zeroed the calipers at .250 which was the size of the holes.

[@alleznape]

@@MrPragmaticLee Ahh, Now I remember you doing that. I didn't understand why at the time and I promptly forgot about it. Now that you explained that trick it's probably my most important take away from the vid I always struggle with centers when I can't measure them directly and I need to build a spanner for a hyd cylinder in a cavity that has the rod sticking out making access limited. Thank you so much!

[@andreventer3837]

Thank you Sir it certainly helps reboot the memory. I did forget that some time ago.

[@jasonhull5712]

All clear as day, except the sin information.. not sure if that’s a standard number used across all hole patterns or was just for this particular pattern. But thanks for the lesson. I’ve always sucked at math, always found crud way’s around it to fabricate whatever I was working on. But now that I’m older I’m trying to get more accurate and learn the proper ways for machining the correct way. Thanks for time.

[@kermitfrog6350]

Seems that marking the center would also be critical. Would be easier while already set up for drilling I think.

[@robertkennedy5374]

It goes unsaid, but a very important part of the process. Not the end of the world but another thing you could have done to make it more fun. I've done things like that all my life. I survived.

[@alanjackson4397]

Very informative video I would much like to see the manual layout procedure

[@tdg911]

Thank you sir, this helped explain a lot for me.

[@joewest2560]

When you run your tap, how do you time the amount of speed on the quill down feed? I mean the quill doesn't free slide down if you pull on it, so if the dow. Speed is off won't the tap strip out the hole? I never understood that. On a lathe the tailstock feeds freely toward the workpiece, but that's different than a mill, no?

[@stevechambers9166]

Well explained 👍👍👍

[@RustyEast]

I just used this function on the dro yesterday to drill and tap the bolt holes for the cylinder head on a PM research steam engine.

[@fiveeightdrumstudio3499]

This may be a dumb question, I usually hand tap and don’t get why powerfeeding taps in and out doesn’t snap the taps ever, is it because it’s a thin material or a through hole? Sometimes I see people doing with thick stuff in blind holes not using a cnc

[@harrisonaero]

Great edit Lee, thanks :)

[@JimG31547]

Lee thanks for the math lesson.

[@johnbarnwell400]

Thank you ! This helped me so much !

[@noneofabove5586]

Nice explanation

[@harlech2]

Another great video!

[@onetireonfire2777]

Excellent video

[@outsidescrewball]

Enjoyed…nice tutorial

[@bsracer85]

Very interesting video. Thanks. But for me, if I saw right, after you determined the hole diameter you measured from outside of one hole to the opposed out side of the next hole with your calipers. Not the center of each hole. does this still work or did you subtract .250 from you measurement?

[@MrPragmaticLee]

I set the calipers at .250 and then ZEROED them. A common way to measure center to center with digital calipers.

[@bsracer85]

@@MrPragmaticLee Thanks for getting back to me. Now that you say it I remember your saying so. I have trouble with digital always having a dead battery.

[@hfanarof8822]

Hi Lee. You mentioned Harold At ARW. Could you please let me know what the full channel name is? Thanks

[@MrPragmaticLee]

Amateur Redneck Workshop.kzbin.info

[@hfanarof8822]

Thanks

[@tallswede80]

also you can use a cad program and create a sketch

[@davidcouling7490]

Interesting...many thanks...

[@deecee3573]

all i need is a piece of paper and a small hamer with a rounded end on one side ,place the paper on the flange and trace the id and od and the holes with the rounded end of the hamer than plavce the paper on the workpiece and your set to dril the holes , no mesuring no formulas no calculations ,no wurys ,greets from a retyerd ships engineer

[@robertkennedy5374]

Too easy to learn on your own. Shipfitters and such learn some great fab techniques.

[@G1951-w1y]

Zero at 3:00 o'clock then counterclockwise is the same as Autocad.

[@Mac-mu9cs]

Why do you zero the calipers?

[@jodydavis161]

Mr Lee I would love to see laying this out bay hand I do not have a mill

[@CraigLYoung]

Thanks for sharing 👍

[@TheCraneman66]

Outstanding Thank you

[@thomaschandler8036]

Good job, but I would like to see the process without the DRO

[@ArcticBlues1]

Thank you :) You Rock!

[@TheMaddogronh]

Thanks for the video,,

[@c2hh571]

Would you explain "center of the hole" It looked like you were using the distance from outer edge to outer edge of next hole. Mathematically, Is this the same as the center?

[@MrPragmaticLee]

I measured to the outside edges “after” setting my digital calipers to .250 (diameter of holes) and then zeroing them. I explained that just before making the measurements. Thanks for stopping by.

[@c2hh571]

@@MrPragmaticLee I heard you explain setting the calipers to zero but I did not know the reason. As you were explaining , my wife was trying to get my attenion to tell me how up set she was about the Royals having some big fight about a house (castle). I did want to be rude to her but just about every time I watch machine vedios she starts in about something I could care less about. Thanks for taking the time.

[@TrPrecisionMachining]

good video..thanks for your time

[@ronlackey674]

Lee, I’m terrible at math where did the 180 come from in the formula? Thanks for your great video.

[@Tom-ic7hw]

got it well done well worth a sub and a like

[@Ue333ue]

I did exactly what you did to find the sin of 36 on my iPhone calculator and came up with a totally different number than what you got

[@trogpot]

Good video

[@jerrywilson9730]

Thanks, this really helps

[@jessestone9117]

I would like to see it

[@77.88.]

You are going in the opposite direction how does that work with backlash? Yes I am a math dummy. Next, I don't have a DRO, but enjoyed your video!

[@simpleman283]

I've spent the last year & a 1/2 learning all the math I need to do a bolt hole pattern w/out DRO, right here on youtube. Where I started was learning what sin & cos was. Then the unit circle, those w/the law of sine & you will have what U need. The really cool part is that it's all free, it just takes time. Search for "sin & cos" look for video by Math and Science, to me Jason is the best. Learning math is fun, when you can do it at your own pace & take breaks when you start getting overloaded. Have fun & Good luck.

[@leftturn99]

More holes make more patterns!

[@reddnmilla]

Good stuff

[@jeremycable51]

I’ve got to get me a dro it’s an incredibly handy tool

[@frankmora8336]

Yes I dont have a dro and would be interested in doing a bolt hole pattern with dividers. Interesting video otherwise.

[@paulmorrey733]

Thanks

[@terrywillis5784]

Yes

[@harrismagnum04]

Thankyou

[@ronlackey674]

Lee great video,just one question where did the 180 come from. I’m terrible at math thanks !

[@metalworksmachineshop]

👍

[@tobymichaels8171]

TL:DW. Fewer words, more information please

[@MegaRiffraff]

👍🏻