Screws in Phenolic Resin
It is possible to affix and attach to phenolic resin countertops and shelves using either sheet metal screws or machine screws. In this post, we share some tips and techniques.
Not to be confused with epoxy resin, phenolic resin (sometimes referred to as high-pressure laminate - HPL) is an excellent lab countertop and shelving material - see Favorite Lab Wall Shelving. Occasionally, it's necessary to use screws for affixing:
- phenolic countertops to cabinets
- brackets to phenolic shelves
- lips to the front of phenolic shelves
Fortunately, it's easy to run either sheet metal screws or machine screws into phenolic.
Sheet Metal Screws
Usually, sheet metal screws will be the quickest and easiest fastener to use when attaching to phenolic resin countertops or shelves. Selecting the right pilot drill type and size is necessary. And, using a stop collar ensures you don't drill too far—through the other side.
Pilot Drills - Type
We recommend using titanium nitride (TiN) coated drills when machining pilot holes for screws in phenolic. The TiN coating is wear-resistant and reduces friction. These drills hold up better than standard uncoated and black oxide-coated drill bits. They are gold in color and readily available at big box stores.
Pilot Drills - Diameters
The following chart shows pilot drill diameters and recommended length of engagement (2 to 2-1/2 screw diameter) for #8 and #10 sheet metal screws.
|Screw Size||Pilot Drill Dia.||Min. Screw Engagement|
|#8||9/64"||3/8" - 1/2"|
|#10||11/64"||1/2" - 5/8"|
Utilizing a stop collar on the pilot drill reduces the potential of drilling too deep into the phenolic material. We like to use clamping two-piece shaft collars that have two Allen screws instead of traditional drill stop collars that have only a single Allen screw. The clamping collars are easy to position and secure to the drill bit.
Note: Clamping collars are not available in 1/64" increments, so we use:
- 4mm ID collar with 9/64" diameter pilot drill
- 3/16" ID collar with 11/64" diameter pilot drill
The following table shows the math:
|Clamping Collar Inside Dia.||Pilot Drill Dia.||Difference (Collar ID - Drill Dia.)|
|4mm (0.1575")||9/64" (0.1406")||0.0169"|
|3/16" (0.1875)||11/64 (0.1719")||0.0156"|
You can use machine screws to attach to phenolic resin following the same drilling and tapping procedure used when working with steel or aluminum. Usually, you'll be tapping into a closed-end hole as opposed to a through-hole. We like to use chip-clearing plug-chamfer taps designed for closed-end holes. And, again, we prefer to use titanium nitride (TiN) coated drills and taps.
We use the following tap drill sizes:
|Machine Screw Size||Tap Drill Size|