A helix is a curve turning about an axis on the surface of a cylinder (cylindrical helix) or cone (conical helix) while rising at a constant upward angle from a base.

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<h1 class="title topictitle1" id="ariaid-title1">Drawing helixes</h1>

<div class="body conbody">
<p class="p">A helix is a curve turning about an axis on the surface of a cylinder (cylindrical helix) or cone (conical helix) while rising at a constant upward angle from a base.</p>
<p class="p">A spiral is a planar curve that winds around a fixed center point at a continuously increasing distance from that point.</p>
<p class="p">The HELIX command can create both 3D helixes and 2D spirals.</p>
<figure class="fig fignone" id="GD_drawinghelixes__fig_alz_f5z_tqb"><img class="image icon" id="GD_drawinghelixes__image_opb_l5z_tqb" src="https://static.bricsys.com/help/images/V23/en_INTL/helix.png">
</figure>
<p class="p">The Helix tool is available on:</p>
<ul class="ul" id="GD_drawinghelixes__ul_ty2_n5z_tqb">
<li class="li">the <span class="ph uicontrol">Draw</span> menu</li>
<li class="li">the <span class="ph uicontrol">Polylines</span> toolbar</li>
<li class="li">the <span class="ph uicontrol">Draw</span> ribbon panel</li>
</ul>
<section class="section" id="GD_drawinghelixes__section_pnz_p5z_tqb"><h2 class="title sectiontitle">General procedure to draw a spiral</h2>

<ol class="ol" id="GD_drawinghelixes__ol_ecw_q5z_tqb">
<li class="li">Launch the HELIX command.<p class="p">Number of turns = 3 Twist = CCW</p><p class="p"><strong class="ph b">You are prompted</strong>: Specify center point of base:</p></li>
<li class="li">Specify a point.<p class="p">Specify base radius or [Diameter] &lt;1&gt;:</p></li>
<li class="li">Do one of the following:<ul class="ul" id="GD_drawinghelixes__ul_ngv_v5z_tqb">
<li class="li">Specify a point.</li>
<li class="li">Type a value, then press Enter.</li>
</ul><p class="p"><strong class="ph b">You are prompted</strong>: Specify top radius or [Diameter] &lt;base radius&gt;:</p></li>
<li class="li">Do one of the following:<ul class="ul" id="GD_drawinghelixes__ul_nrm_bvz_tqb">
<li class="li">Specify a point.</li>
<li class="li">Type a value, then press Enter.</li>
</ul><p class="p"><strong class="ph b">You are prompted</strong>: Specify helix height or [Axis endpoint/Turns/turn Height/tWist] &lt;1&gt;:</p></li>
<li class="li">Type 0 (zero), then press Enter</li>
</ol>
</section>
<section class="section" id="GD_drawinghelixes__section_l1m_hvz_tqb"><h2 class="title sectiontitle">General procedure to draw a helix</h2>

<figure class="fig fignone" id="GD_drawinghelixes__fig_n53_jvz_tqb">
<br><div class="imageleft"><img class="image imageleft" id="GD_drawinghelixes__image_kkk_kvz_tqb" src="https://static.bricsys.com/help/images/V23/en_INTL/Helix_Steps.png"></div><br>
</figure>
<ol class="ol" id="GD_drawinghelixes__ol_wbt_kvz_tqb">
<li class="li">Launch the HELIX command.<p class="p">Number of turns = 3 Twist = CCW</p><p class="p"><strong class="ph b">You are prompted</strong>: Specify center point of base:</p></li>
<li class="li">Specify a point (1).<p class="p"><strong class="ph b">You are prompted</strong>: Specify base radius or [Diameter] &lt;1&gt;:</p></li>
<li class="li">Do one of the following (2):<ul class="ul" id="GD_drawinghelixes__ul_rgj_rvz_tqb">
<li class="li">Specify a point.</li>
<li class="li">Type a value, then press Enter.</li>
</ul></li>
<li class="li">Do one of the following (3):<ul class="ul" id="GD_drawinghelixes__ul_ys3_zvz_tqb">
<li class="li">Press Enter to set the top radius equal to the base radius, thus creating a cylindrical helix.</li>
<li class="li">Specify a point.</li>
<li class="li">Type a value, then press Enter.</li>
</ul><p class="p"><strong class="ph b">You are prompted</strong>: Specify helix height or [Axis endpoint/Turns/turn Height/tWist] &lt;1&gt;:</p></li>
<li class="li">Do one of the following (4):<ul class="ul" id="GD_drawinghelixes__ul_mh5_2wz_tqb">
<li class="li">Specify a point.</li>
<li class="li">Type a value, then press Enter.</li>
</ul></li>
</ol>
</section>
<section class="section" id="GD_drawinghelixes__section_ybm_gwz_tqb"><h2 class="title sectiontitle">Editing a helix</h2>

<ol class="ol" id="GD_drawinghelixes__ol_lgl_hwz_tqb">
<li class="li">Select the helix.<p class="p">The helix properties display in the <span class="ph uicontrol">Geometry</span> category in the <span class="ph uicontrol">Properties</span> panel.</p></li>
<li class="li">Edit the properties:<ul class="ul" id="GD_drawinghelixes__ul_cyd_lwz_tqb">
<li class="li"><span class="ph uicontrol">Constrain</span>: constrains either the height, turn height or number of turns. The unconstrained properties are adjusted automatically.</li>
<li class="li"><span class="ph uicontrol">Height</span>: Overall height of the helix. height = turn height * turns.</li>
<li class="li"><span class="ph uicontrol">Turns</span>: Number of turns.</li>
<li class="li"><span class="ph uicontrol">Turn height</span>: Height of one turn.</li>
<li class="li"><span class="ph uicontrol">Base radius</span>: start radius.</li>
<li class="li"><span class="ph uicontrol">Top radius</span>: end radius.</li>
<li class="li"><span class="ph uicontrol">Twist</span>: direction CW (Clockwise) or CCW (Counterclockwise).</li>
</ul></li>
</ol>
<div class="p">
<div class="note note note_note"><span class="note__title">Note:</span> 
<ul class="ul" id="GD_drawinghelixes__ul_x3x_vwz_tqb">
<li class="li">Set the <span class="ph uicontrol">Top radius</span> = <span class="ph uicontrol">Base radius</span> for cylindrical helixes.</li>
<li class="li">Set <span class="ph uicontrol">Height</span> or <span class="ph uicontrol">Turn height</span> to zero for spirals.</li>
<li class="li">The EXPLODE command turns a helix into a spline.</li>
</ul>
</div>
</div>
</section>
</div>
<nav role="navigation" class="related-links"><div class="familylinks"><div class="parentlink"><strong>Parent topic:</strong> <a class="link" href="/en-us/document/bricscad?version=V23">BricsCAD</a></div></div><div class="familylinks"><div class="parentlink"><strong>Parent topic:</strong> <a class="link" href="/en-us/document/bricscad/2d-drafting?version=V23">2D Drafting</a></div></div><div class="linklist"><strong>Related commands</strong><br><ul class="linklist"><li class="linklist"><a class="link" href="/en-us/document/command-reference/h/helix-command?version=V23" title="Creates a 2D spiral or a 3D helix.">HELIX command</a></li><li class="linklist"><a class="link" href="/en-us/document/command-reference/3/3dpoly-command?version=V23" title="Creates a 3D polyline.">3DPOLY command</a></li><li class="linklist"><a class="link" href="/en-us/document/command-reference/s/spline-command?version=V23" title="Creates a spline.">SPLINE command</a></li><li class="linklist"><a class="link" href="/en-us/document/command-reference/p/pline-command?version=V23" title="Creates a polyline.">PLINE command</a></li></ul></div><div class="linklist"><strong>Related information</strong><br><ul class="linklist"><li class="linklist"><a class="link" href="/en-us/document/bricscad/panels/properties-panel?version=V23">Properties panel</a></li><li class="linklist"><a class="link" href="/en-us/document/bricscad/drawing-accurately?version=V23">Drawing accurately</a></li><li class="linklist"><a class="link" href="/en-us/document/bricscad/drawing-accurately/dynamic-dimensions?version=V23">Dynamic dimensions</a></li></ul></div></nav>
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