# Extrude Precision and precision in general
**URL:** https://discourse.shapr3d.com/t/extrude-precision-and-precision-in-general/12815
**Category:** Modeling Questions
**Created:** [May 16, 2021, 3:53pm UTC](https://discourse.shapr3d.com/t/extrude-precision-and-precision-in-general/12815 "2021-05-16T15:53:58Z")
**Posts on this page:** 17
**Page:** 1
### Author:  [@UCS308](https://discourse.shapr3d.com/u/UCS308)
#### Post date: [May 16, 2021, 3:53pm UTC](https://discourse.shapr3d.com/t/extrude-precision-and-precision-in-general/12815/1 "2021-05-16T15:53:58Z")
I am going back and forth trying to get a body extruded to a precise length 1016mm. But everything I do gives me a fraction. When I try and remove just that fraction it removes some other value larger ( i am using the pad to key in my values). It looks like it might be double but not always. I assume this is a bug? I am using an iPad.
What would be useful, and maybe there is a way to do this that I have not found, is to be able to set the precision. For example if I am working in mm, for my application, I don’t need things moved, sized or positioned in fractions of 1mm. I understand others might.
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### Author:  [@Istvan](https://discourse.shapr3d.com/u/Istvan)
#### Post date: [May 16, 2021, 4:04pm UTC](https://discourse.shapr3d.com/t/extrude-precision-and-precision-in-general/12815/2 "2021-05-16T16:04:12Z")
Can you share the workspace or a screenshot? I tried but I can’t reproduce the problem.
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### Author:  [@andrew](https://discourse.shapr3d.com/u/andrew)
#### Post date: [May 16, 2021, 4:18pm UTC](https://discourse.shapr3d.com/t/extrude-precision-and-precision-in-general/12815/3 "2021-05-16T16:18:59Z")
This sounds like another vote for constraints on bodies/extrusions…
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### Author:  [@UCS308](https://discourse.shapr3d.com/u/UCS308)
#### Post date: [May 16, 2021, 4:51pm UTC](https://discourse.shapr3d.com/t/extrude-precision-and-precision-in-general/12815/4 "2021-05-16T16:51:35Z")
The model is not very exciting so I can send you the shapr file if you like.
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### Author:  [@UCS308](https://discourse.shapr3d.com/u/UCS308)
#### Post date: [May 16, 2021, 4:52pm UTC](https://discourse.shapr3d.com/t/extrude-precision-and-precision-in-general/12815/5 "2021-05-16T16:52:49Z")
Well I am voting for specified precision. 😀
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### Author:  [@Istvan](https://discourse.shapr3d.com/u/Istvan)
#### Post date: [May 16, 2021, 6:07pm UTC](https://discourse.shapr3d.com/t/extrude-precision-and-precision-in-general/12815/6 "2021-05-16T18:07:53Z")
Please send the file to me ([istvan@shapr3d.com](mailto:istvan@shapr3d.com)) or to [support@shapr3d.com](mailto:support@shapr3d.com). Also a screenshot of the issue would be szper helpful.
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### Author:  [@UCS308](https://discourse.shapr3d.com/u/UCS308)
#### Post date: [May 19, 2021, 4:46pm UTC](https://discourse.shapr3d.com/t/extrude-precision-and-precision-in-general/12815/7 "2021-05-19T16:46:51Z")
Any thoughts on this? It is really a pain that I can’t size things without guessing what number shapr is going to come up with.
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### Author:  [@UCS308](https://discourse.shapr3d.com/u/UCS308)
#### Post date: [May 19, 2021, 4:58pm UTC](https://discourse.shapr3d.com/t/extrude-precision-and-precision-in-general/12815/8 "2021-05-19T16:58:44Z")
OK. I just tested this with a body that has square or rectangular face. When I try and resize I am always give the option to enter the whole size. After I chamfer the edge to 45 degrees - I am making mitered carcasses - I am given the option to move the face by an amount relative to the current size. When I do that shapr starts to introduce rounding errors, that after a few attempts devolves into full on errors.
For example. If I have a panel that has an outside edge of 450mm and inside edge of 430mm, I select the top face and reduce the size by -10mm my outside edge is now 435.858 the inside edge is 415.858, the material is 20mm thick. I expected the outside edge to be 440mm and the inside edge to be 420mm.
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### Author:  [@Istvan](https://discourse.shapr3d.com/u/Istvan)
#### Post date: [May 19, 2021, 6:16pm UTC](https://discourse.shapr3d.com/t/extrude-precision-and-precision-in-general/12815/9 "2021-05-19T18:16:59Z")
Can you please post a screenshot?
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### Author:  [@UCS308](https://discourse.shapr3d.com/u/UCS308)
#### Post date: [May 19, 2021, 8:06pm UTC](https://discourse.shapr3d.com/t/extrude-precision-and-precision-in-general/12815/10 "2021-05-19T20:06:54Z")
I already sent you a model. Here are three screen shots. You should note that the new size is random, or maybe a ratio of the size of the panel I am sizing.
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### Author:  [@Istvan](https://discourse.shapr3d.com/u/Istvan)
#### Post date: [May 19, 2021, 8:10pm UTC](https://discourse.shapr3d.com/t/extrude-precision-and-precision-in-general/12815/11 "2021-05-19T20:10:20Z")
This is the expected behavior. Using the offset operation offsets a face in the direction of its normal, so when you are offsetting that face it won’t move in the Z direction. If you want to move that face in a certain direction, you can use the Move/Rotate tool to move it.
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### Author:  [@UCS308](https://discourse.shapr3d.com/u/UCS308)
#### Post date: [May 19, 2021, 8:48pm UTC](https://discourse.shapr3d.com/t/extrude-precision-and-precision-in-general/12815/12 "2021-05-19T20:48:06Z")
Fine. But can I move it with precision? I mean sometimes it is out by 5 or 10 or 50mm. I mean I need to make that board a certain length. Otherwise how can I layout the furniture for with any accuracy. And this is simple stuff.
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### Author:  [@Istvan](https://discourse.shapr3d.com/u/Istvan)
#### Post date: [May 19, 2021, 8:53pm UTC](https://discourse.shapr3d.com/t/extrude-precision-and-precision-in-general/12815/13 "2021-05-19T20:53:46Z")
Yes, absolutely. That’s what the Move/Rotate tool does. You can precisely move faces, edges and bodies with it.
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### Author:  [@UCS308](https://discourse.shapr3d.com/u/UCS308)
#### Post date: [May 19, 2021, 9:35pm UTC](https://discourse.shapr3d.com/t/extrude-precision-and-precision-in-general/12815/14 "2021-05-19T21:35:30Z")
OK. But for clarity. You are saying that offsetting by 14mm when asking for 20mm is the expected behavior when using the offset face.
And in case it is not clear, I really like Shapr3D, so far. Just a bit confusing.
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### Author:  [@Istvan](https://discourse.shapr3d.com/u/Istvan)
#### Post date: [May 19, 2021, 9:38pm UTC](https://discourse.shapr3d.com/t/extrude-precision-and-precision-in-general/12815/15 "2021-05-19T21:38:17Z")
No, that’s not what I mean. Offsetting 20mm a 45° chamfer will shorten your edge on the side by exactly 10 \* √2. Offsetting does not move the face in the Z direction, but in the direction of the normal of the face.
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### Author:  [@Istvan](https://discourse.shapr3d.com/u/Istvan)
#### Post date: [May 19, 2021, 9:45pm UTC](https://discourse.shapr3d.com/t/extrude-precision-and-precision-in-general/12815/17 "2021-05-19T21:45:40Z")
Offset (blue) vs move (red):
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### Author:  [@UCS308](https://discourse.shapr3d.com/u/UCS308)
#### Post date: [May 26, 2021, 4:55am UTC](https://discourse.shapr3d.com/t/extrude-precision-and-precision-in-general/12815/18 "2021-05-26T04:55:57Z")
Thank-you. I am progressing… Getting the hang of it.