Knowledge · Design
Design limits: what your sheet metal part can take
A sheet metal part follows a handful of geometric rules: a hole cannot be arbitrarily small, a flange needs room in the tool, and a hole too close to a bend will distort. These are the guide values you can use to assess your own design. Nothing is blocked here – we check every file by hand. If your part falls outside the table, send it anyway.
Calculator
Pick material and thickness – all guide values at once
Two dropdowns, and below them everything that applies to that combination. Each value with a sentence on what it means. The same figures appear in the tables further down.
available directly
Smallest hole diameter
2.25 mm
Smaller holes we drill instead of cutting. Below 1 mm even that is not possible.
Narrowest web
3 mm
The narrowest strip of material between two contours.
Distance to outer edge
3.2 mm
From a cut-out to the edge of the part. Any closer and the edge becomes unstable.
Bending
possible, die V16
Measured from the outer edge. Shorter flanges the tool cannot hold.
Inside radius
2.5 mm
Determined by the tool, not by your drawing.
Distance contour to bend
13 mm
The same value as the minimum flange, also from the outer edge. Any closer and the hole distorts while bending.
Relief slot
1.2 mm
Width of the slot if the distance to the bend is not sufficient.
Threads
M3–M12
From 1.5 mm sheet thickness. Below that too few threads engage – press-in or weld nuts are the better choice.
Tapping drill, if you cut the thread yourself
- M3 2.50
- M4 3.40
- M5 4.30
- M6 5.10
- M8 6.90
- M10 8.60
- M12 10.30
Stainless steel values, one tenth larger
Guide values for your design. Nothing is blocked – we check every file by hand.
Material
Ten materials, two routes to a thickness
The left column you order directly in the calculator. The right one is available too – we source it for you, and it pays off from larger quantities. “On request” is not a no, just a short extra step.
| Material | Grade | Available directly | On request, from larger quantities |
|---|---|---|---|
| Steel (S235) | S235 | 0.5–20 mm | – |
| Steel (S355) | S355 | 0.5–20 mm | – |
| S235 galvanised | S235 verzinkt | 0.5–6 mm | – |
| DD11 / DC01 | DD11 / DC01 | 0.5–15 mm | – |
| HB 400 (wear-resistant plate) | HB 400 | 0.5–15 mm | – |
| Stainless steel V2A 1.4301 | V2A 1.4301 | 0.5–15 mm | – |
| Stainless steel V4A 1.4404 | V4A 1.4404 | 0.5–10 mm | up to 15 mm |
| Stainless steel V4A 1.4571 | V4A 1.4571 | 0.5–10 mm | up to 15 mm |
| Aluminium AlMg3 | AlMg3 | 0.5–12 mm | up to 15 mm |
| Corten (weathering steel) | Corten | 0.5–3 mm | up to 15 mm |
Not every thickness and grade is in stock at all times. Common materials and thicknesses are always available, rarer combinations are ordered in – which can extend the lead time. Read the table as our range, not as a guarantee of availability.
Laser cutting
Hole, web and edge distance all follow the thickness
A laser beam is not a needle: it needs a minimum width to cut through the full thickness. Three formulas are enough to check a design in your head.
Hole
Smallest hole diameter
Ø ≥ 0.75 × s · Alu: Ø ≥ s
Never below 1 mm – not even in thin sheet, where the formula would allow less.
Web
Narrowest web
b ≥ s
Applies to every material, between any two contours, inside and out. At least 1 mm.
Edge
Distance to outer edge
a ≥ s, at least 3.2 mm
From a cut-out to the outer edge of the part. Any closer and the edge becomes unstable.
| Thickness | Hole Ø steel + stainless | Hole Ø aluminium | Narrowest web | Edge distance |
|---|---|---|---|---|
| 0.5 mm | 1 mm | 1 mm | 1 mm | 3.2 mm |
| 1 mm | 1 mm | 1 mm | 1 mm | 3.2 mm |
| 1.5 mm | 1.13 mm | 1.5 mm | 1.5 mm | 3.2 mm |
| 2 mm | 1.5 mm | 2 mm | 2 mm | 3.2 mm |
| 2.5 mm | 1.88 mm | 2.5 mm | 2.5 mm | 3.2 mm |
| 3 mm | 2.25 mm | 3 mm | 3 mm | 3.2 mm |
| 4 mm | 3 mm | 4 mm | 4 mm | 4 mm |
| 5 mm | 3.75 mm | 5 mm | 5 mm | 5 mm |
| 6 mm | 4.5 mm | 6 mm | 6 mm | 6 mm |
| 8 mm | 6 mm | 8 mm | 8 mm | 8 mm |
| 10 mm | 7.5 mm | 10 mm | 10 mm | 10 mm |
| 12 mm | 9 mm | 12 mm | 12 mm | 12 mm |
| 15 mm | 11.25 mm | 15 mm | 15 mm | 15 mm |
| 20 mm | 15 mm | – | 20 mm | 20 mm |
Aluminium gets no reduction: it reflects more and melts differently, so the smallest hole diameter there equals the sheet thickness. And no hole goes below 1 mm – not even in thin sheet, where the formula would allow less. How to get clean contours into your file is covered in our guide Create a DXF file.
Bending
The X dimension is measured from the outer edge
When bending, the tool sets the rules: the die determines the inside radius and how short a flange may be. The same value applies to the distance between a hole and the bend – and both are measured from the outer edge of the part, not from the bend line.
| Thickness s | Die | Minimum flange X | Bend radius R | Contour → bend |
|---|---|---|---|---|
| 0.5 mm * | V8 | 6 mm | 0.5 mm | 6 mm |
| 1 mm | V8 | 6 mm | 1 mm | 6 mm |
| 1.5 mm | V8 | 6.5 mm | 1.5 mm | 6.5 mm |
| 2 mm | V12 | 10 mm | 2 mm | 10 mm |
| 2.5 mm | V16 | 13 mm | 2.5 mm | 13 mm |
| 3 mm | V16 | 13 mm | 2.5 mm | 13 mm |
| 4 mm | V32 | 25 mm | 4 mm | 25 mm |
| 5 mm | V32 | 25 mm | 5 mm | 25 mm |
| 6 mm | V50 | 35 mm | 6 mm | 35 mm |
* The tooling table starts at 1.0 mm. We also bend 0.5 mm sheet – V8 applies accordingly there. The distance from contour to bend always equals the minimum flange X and is measured from the outer edge.
Boxes and trays
We make boxes and trays up to a height of 100 mm. Taller parts are possible too: we cut slots into the bend radii, pre-bend to the maximum achievable angle and finish the rest by hand – the slots are then welded up again where needed.
Z-bends
If two bends sit very close together, the tool can no longer reach the second one. Design the angle flatter than 90° in that case – that gives the upper tool the clearance it needs.
Above the bending limit
We do not bend above 6 mm. Cutting remains possible, in steel up to 20 mm. For thick brackets and angles, welding two blanks together is usually the better solution than a bend.
When it gets tight
Relief slots and corners on welded parts
Two details that often help a design more than a thicker wall: a narrow slot that takes the strain out of the bend zone, and a corner that can actually be welded.
How to relieve a bend zone
If the distance to the bend cannot be maintained in your design, a narrow slot takes the stress out of the zone. The shape matters: sharp internal corners weaken the material and start cracks. A slot or a rectangular cut-out with rounded corners holds; a sharp rectangle tears.
We give fixed widths up to 4 mm thickness: 0.8 mm for 1–2 mm, 1.2 mm for 2.5–4 mm. Above that we agree the value with you – just sketch where it gets tight.
Corners that can be welded
On parts that are welded afterwards we leave out corner relief cuts. Instead the two corners butt against each other with roughly 0.1 mm of clearance. That gives a closed corner which can be welded in one pass – with no notch that stays visible later or has to be filled.
In the flat pattern this means: both flanges keep their full length up to the corner, and in the file they sit corner to corner – not overlapping, and without a notch between them.
Threads + countersinks
Tapping drill or finished thread – draw one of the two
We cut exactly what is in the file. If you tap the thread yourself, draw the tapping drill size from the table. If we take care of the thread, simply draw the finished thread – the tapping drill is then our business.
| Thread | Pitch | Tapping drill Ø standard | Tapping drill Ø stainless |
|---|---|---|---|
| M3 | 0.50 mm | 2.50 mm | 2.50 mm |
| M4 | 0.70 mm | 3.30 mm | 3.40 mm |
| M5 | 0.80 mm | 4.20 mm | 4.30 mm |
| M6 | 1.00 mm | 5.00 mm | 5.10 mm |
| M8 | 1.25 mm | 6.80 mm | 6.90 mm |
| M10 | 1.50 mm | 8.50 mm | 8.60 mm |
| M12 | 1.75 mm | 10.20 mm | 10.30 mm |
Why stainless steel gets one tenth more
A slightly larger tapping drill takes torque off the tap. More than one tenth would be counterproductive: in sheet metal only a few threads engage anyway, and those need to carry the load. M3 therefore stays unchanged – there even one tenth would weigh too heavily.
When is a thread worth it?
From 1.5 mm sheet thickness. Below that too few threads engage to transfer load – press-in or weld nuts are the better choice there. We recognise both from your drawing.
Countersinks
The calculator detects countersinks directly from your CAD file and prices them in. Simply draw them as countersinks – through hole, countersink diameter and depth are all picked up.
Size
Up to the full sheet
The largest sheet measures 3000 × 1500 mm; nesting also runs 2500 × 1250 and 2000 × 1000 mm. Slightly less is usable in each case: edges and webs between the parts need space.
There is essentially no weight limit – if a part gets too heavy or too large for a parcel, it ships by freight forwarder. When bending, the bend length is the limit, not the weight.
3000 × 1500
Largest sheet size in mm
3000
Maximum bend length in mm
100
Box height in mm
no limit
Weight per part
FAQ
Frequently asked questions about design limits
Can I have a 2 mm hole in 5 mm sheet?
In 5 mm steel or stainless steel the smallest hole diameter is 3.75 mm – so a 2 mm hole is too small there. In 2.5 mm sheet it just works at 1.88 mm. If you need the small hole, either choose the thinner sheet or have it drilled rather than cut. Send us the file and we will tell you what makes more sense for your part.
How far does a hole need to be from a bend?
As far as the minimum flange length X for that thickness, measured from the outer edge of the part – 13 mm at 3 mm, 25 mm at 5 mm. Any closer and the hole distorts while bending. If the distance is not possible in your design, a narrow slot in the bend zone takes the strain out.
Which tapping drill do I need for M6 in stainless steel?
5.10 mm in stainless steel instead of the usual 5.00 mm. The slightly larger hole takes torque off the tap without weakening the thread. Only draw the tapping drill if you cut the thread yourself – if we cut it, draw the finished thread instead.
What is the maximum thickness you can bend?
Up to 6 mm. Above that we still cut the flat blank, but we do not bend it. The maximum bend length is 3000 mm.
What happens if my part does not meet these guide values?
Nothing is blocked. The calculator accepts your file and we check every file by hand. If a detail cannot be made as drawn, we come back to you with a suggestion – usually a small change is enough. The values on this page are guide values for your design, not an acceptance rule.
I am unsure about the sheet thickness – how should I decide?
Start from your smallest detail, not from stiffness: the smallest hole and the narrowest web limit the thickness upwards, rigidity limits it downwards. The calculator above shows you both sides for every combination. And if you are torn between two thicknesses, just ask us – that is quicker than guessing.
How large can my part be?
Up to the full sheet size of 3000 × 1500 mm. Slightly less is usable because edges and webs need space in the nesting. Larger or heavy parts ship by freight forwarder rather than parcel.
Does the bending table also apply to aluminium and stainless steel?
Yes, the values for die, radius and minimum flange are the same for all materials. Differences in springback are compensated at the machine – the angle monitoring corrects them during the process.
Does your design fall outside the table? Send it anyway.
The values here are guide values, not a barrier. Nothing is blocked in the calculator – we check every file by hand and tell you what is possible. Often that is more than the table suggests.
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