Setting diameter or circle and length of line

mark_nahabedian

I'm using the browser interface in Chrome of Ina Windows Surface laptop.

In a sketch, I'm trying to set the length of a line.  I use the line tool to draw a line.  When I then click on the length box to edit the length to the value of a variable, instead OnShape starts to draw another line.

I undo the new line, select the first line and click on the "length" display in the bottom right corner to edit it.  If I then start typing the variable reference beginning with an octathorpe (sharpsign) the viewport changes.  I can then type the expression defining the length of the line and hit return.  When I do this though, rather than setting the length of my line, OnShape creates a new line parallel to the first at some distance from it.

I experience similar behavior when trying to set the diameter of a circle.  Instead I get a new circle concentric to the first whose RADIUS is my specified amount greater than the original circle whose diameter I wanted to set.

I realize I can use the dimension tool to constrain the length of a line or the diameter of a circle, my my sketch gets very cluttered when I do that.

What should I be doing?

NeilCooke

The ONLY way to constrain a sketch is to add constraints and dimensions. This is what makes the system parametric. 

When the length box appears, just type a value (don’t click), however this will add a dimension.  The length display in the bottom right corner is a read only measurement. 

mark_nahabedian

Thanks Neil.  That was a big help

 I still get the weird viewport behavior i(I wind up viewing from the edge Iof the sketch plain rather than normal to it) start the length with a sharpsign to refer to a variable, but I can work around that.

Is there a way to control whether dimensions are shown like one can for other constraints?

NeilCooke

You can press the N key to view normal to the sketch plane. 

You can’t enter a variable straight away. You have to accept the default value then edit it afterwards to change it to a variable. 

Dimensions are always on. If the sketch is getting cluttered it could be that your sketches are getting too complicated. Best to split them up into multiple smaller sketches. 

mark_nahabedian

Upper case "N", as it appears in all of the documentation, doesn't work for me, but I just found that lower case "n" does switch to a view normal to the sketch plane.

My sketch is not complicated: 6 circles, 8 lines.  Take a look at "drill press depth stop mounting bracket" if you want to take a look.  The sketch is cluttered because it's being drawn in an area of about 12 square inches: the remaining screen real estate on a Microsoft Surface laptop.

My sketch is complete.  The part is a simple extrusion from the sketch except that there is a sort of recess in the middle that's not extruded to the same height as the rest, and I've not yet figured out how to do that.  It was pretty easy to use the extrusion tool to select all of the regions for the first extrusion, and OnSgape did a really good job of figuring out what I wanted so I only needed to toggle a couple of regions in the extrusion.  When I try to extrude the less high portion in the middle the relevant sketch lines aren't visible.

mark_nahabedian

I figured out my extrusion problem: my sketch wasn't visible in the part studio.

Thanks so much for your patience and help.

mark_nahabedian

Neil, thanks for all your help.  In case you're interested, here's my completed design:

https://cad.onshape.com/documents/87c734434a3d09a1007f9322/w/822165c65a73fcefc6d8feb9/e/3af9931f54c596289d8aca98

kim_meisel

This doesn't work for me, Neil!

I'm typing and nothing happens. https://imgur.com/KH96QBG

I am using a Chromebook btw.

kim_meisel

now i got it!