42 Replies Latest reply on Aug 26, 2016 2:38 PM by Arthur McRae

Hi,

I am trying to create a flathead Phillips screw as a SolidWorks part.  I was wondering what the best way was to create the Phillips head socket at the top of the screw.  Below is an image of what I am talking about.  Thanks!

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I am looking for the dimensions on how to make the actual Phillips inset part of the head of the screw in SolidWorks.

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What he said

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Robertson is a way better screw design....

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see attachment

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Here are the spec'd dimensions.

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Used specs for a #8

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How do you figure out the draft degree for the Phillips recess?

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If you can reference MIL-STD-9006 " Recesses - Cross,  Low Torque Drive, Dimensions and Gage Dimensions for"  for the dimensions and work backwards from there

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from the second table: atn(G/((M-N)/2))

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I am trying to build a size 6 Flat Head Phillips.  I used the chart you posted and calculated the draft angle based off of what you posted.  However that gave me a draft angle of .4, which seems a little small.  I have attached an image of what I have drawn so far for the Phillips head recess.  I am using metric units on my model (.737mm =.029" & 2.045mm = .0805"

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The draft angle I got was 66.97° => tan^-1 (.106/(.174-.029))

If you turn the controlling parameters into equations you can easily use the imperial units from the chart into the metric part

ie: d1@sketch1 = .106 in

I would add the fillet to the inside of the recess after the cut.

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Don't you have to divide (.106/(.174-.029)) by 2?  When I did that, I got a draft angle of around 20 degrees.  However, my drawing wont allow for a draft angle larger than around 8

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and you are NOT making a drawing - you are making a model, which you could make a drawing from later, if desired.

you will not be able to include the "draft" in the extrude cut - you will need different angles on different faces.

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you are correct good catch

atn(.106/(.174-.029)*.5)

atn(1.46)

55.59 deg

I created a cut from center plane and then did a circular pattern from that in my model so I never had to deal with the draft angle restriction.

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Whenused the dimensions of the phillips recess I am using (G =.106 ; M =.170 ; N=.034) I calculated a draft angle of 89.3 degrees.  Using the equation arctan(G/((M-N)/2)).  This seems like a pretty steep draft angle.  I am having trouble with transferring that over to the part I am making.  When I try to put the draft angle at 89.3 degrees it is too high and comes with an error warning.

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Don't use a draft that steep it will bottom out at an angle before you get the correct depth.

Here I am am using a swept cut to get the first of my cuts, I then use a circular pattern to get all 4 slots, then added the fillet to the inside edges.

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If I did my calculations right I get an 89.3 degree draft angle this seems a little to high because its almost a straight 90 degrees.  Am I not supposed to divide (M-N) by 2 in the equation?

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The dimensions in the model are linked to named Global variables. Change whatever you need.

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How do you go about changing the global variables?

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The problem I am having is that the draft angle is so large, that it would make the depth of the Phillips recess shorter.  I have attached an image to show you.  The "V" is the line that would be part of the draft angle.  The horizontal blue line is where the length of the Phillips recess should be, and the vertical black line is the depth that the recess should be.  As you can see, either the depth of the recess has to be shallower or the length of the recess has to be longer.  I am not sure how to sort out this issue.

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If you are doing this as an academic exercise then you just need to research the shape of the recess better.  The bottom of the recess is blunt, not sharp as you have it here.  That is the immediate problem.  Look at the resources cited above from Arthur McRae and Tony Cantrell who was the first to suggest downloading from McMaster-Carr.

If this is not an academic exercise and you really want fasteners in your library then don't reinvent the wheel.  Either use Toolbox within SWX or download models as others have suggested.

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Don't use a draft that steep it will bottom out at an angle before you get the correct depth.

I already mentioned that would be a problem.  Do a sketch at the center of your screw as you have above, create the profile you want to cut there, you can either fillet the profile to get the curves or you could use a swept cut with your profile held to normal.

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I think the equation earlier was reversed.  I believe it should be arctan((M-N)/2)/G).  This gave me a more sensable angle.  I am still struggling with the swept cut though.  What did you use as your path for the swept cut to follow?

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Just did a an arc as my swept path.

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When I tried sweeping the path, I just got a slice of the cut because it acted more as a revolve than a swept path.

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I also tried doing an extruded cut of a rectangle on the side plane, and then 2 other extruded cuts on the top plane for the angled corners of the Phillips head recess, but I cant get the draft angle correct for the angled corners.

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This is the setting you need to change to get the swept cut to be "squared" up.

I'm not quite sure what you're meaning here:

J. S. wrote:

but I cant get the draft angle correct for the angled corners.

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Nice one Arthur!

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dont reinvent wheel.

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I am making a custom screw.  Its head height is slightly taller than that of the models given on that website.  When I try to edit the model from the website, it throws of the draft of the extruded cut for the Phillips recess.

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Another option is to download the screw from the site of your choice but bring it in as a dumb solid. Then modifications can be made to it without the issue of something further up the tree changing something else.

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A lot of people have suggested to download screws from McMaster. McMaster screws are garbage. They have far too much detail, including threads, and have no design table or other features that would make them useful. Much better to make you own.

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Simplify too much detail. Suppress the Swept Cut. Make that a simplified configuration if you choose to keep both.

I'd make my own part if I was also fabricating my own screw, which is to say I would not. Original poster clearly is. Even so, I'd take their part and rollback as needed to edit and modify to suit. It shows a simple design tree at very least to emulate or improve upon.

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I've taken their models and inserted my own design table, complete with all their information - that works really well and yeah you could strip out all the threads etc...   Don't know if you remember or not we had a McMaster-Carr thread going years ago and the original poster had to delete the entire thread, McMaster-Carr lawyers on the scene....lol - so for a while their was a lot of Anti McMasters

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Ummmm,

So, can a basic McMaster-Carr screw be easily modified or not?

Example, can I just take one, cut it's length down, add a small chamfer to the end and finish rather than create a design table to do the same thing?

Dave.

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Yes

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Yeah - you can change it however you want it - if you have a chance go to 3dcontentcentral.com and in the search bar type in my name and look for a Socket Head Cap Screw - download with configurations and see how I did them, not the best modeling but works......

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Mike,

However,

I do download Die Springs, Shoulder Bolts, Set Screws and other components.

In the tree for the downloaded part I RMB on Equations and select Manage Equations.

Easy peasy to change almost anything.

I really like this to have my Die Springs shown at "Bottom-Dead-Center" compressed condition.

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..next to screw threads,,... the black hole of time/money in the engineering/design world moves ever closer to the event horizon...

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Bit off topic but...

I once had a 5/8" threaded rod going through a plate, the rod got threaded down too far and we couldn't get a double nut on it to turn it back up.

This is what we had to do to the threaded rod, we cut 2 slots in the top with 3/32 wide 4.5" cutting disks and then ran a 3/16" drill bit down the center to a depth of about 1/8"  This allowed us to get a #3 Philips screwdriver into it and get enough torque to back it out enough.  Yet another case of necessity breeding invention.