Hold-downs before hero nests

The first month problem

New owners spend hours learning CAM, then lose a job because a sheet lifted halfway through. Most first-month failures we see are clamps, not toolpaths. Thin acrylic bows, MDF with a slight cup rocks, and small parts spin loose on the last pass.

A simple hold-down order

1. Check the spoilboard is flat where the sheet will sit.
2. Clamp the edges at no more than 300 mm spacing on thin stock.
3. Add screws or tabs in the middle of anything bigger than A3.
4. Leave onion-skin or tabs on small parts so they cannot spin.
5. Dry-run the first path with the spindle off and the Z raised, to check clamp clearance.

Write the map down

Once a job runs clean, draw where the clamps went on a printed outline of the bed and keep it with the job file. The next person to run it does not have to rediscover the same lesson. Our hold-down map card in resources is built for this.

The slip we see most

Trusting double-sided tape on a big sheet because it worked on a small one last week.

How you know it is working

Rejects from lifted sheets drop to almost none, and the clamp map comes out of the job folder without anyone asking.

Written by Thabo Molefe, Plasma Cell Lead. Thabo specs the plasma tables, fixture plates and consumable shelves for steel shops.