Tru-Stone technical assistance, stainless-steel and threaded inserts,holes and slots, LVDT Transducer assemblies

Tru-Stone has the talent and capabilities to help you create the perfect part to serve as a component or the foundation of your design.

The quality of the final product directly relates to our integration of high quality parts, proven methods and workmanship.

More information on the physical properties of different granite types can be found by visiting our Granite Spec Sheets section on our Forms page.

Inserts
stainless-steel inserts, threaded inserts, unified threads, metric threads Inserts might seem as simple as nuts in an assembly, but they play a crucial role for proper assembly of your stage, rails, clamps, etc. to the granite base. If even one insert pulls loose or has poor threads, your entire assembly is compromised.

Tru-stone uses 300-series certified stainless steel inserts so you don’t have to worry about rust. We turn our own inserts in our CNC turning centers and we use proper thread gages for quality control inspection. We turn a specially designed pattern on the outside diameter to maximize holding power of our proprietary mix of epoxy used to secure the inserts.

Minimum insert torque ratings from Federal Specification GGG-P-463c:

Unified Threads		Metric Threads
Thread Size	Torque Rating	Thread Size	Torque Rating
.250"	7 ft. lbs.	M6	10 Nm
.3125"	15 ft. lbs.	M8	20 Nm
.375"	20 ft. lbs.	M10	27 Nm
.500"	25 ft. lbs.	M12	34 Nm
.625"	30 ft. lbs.	M16	41 Nm

Tru-Stone Standard Insert Sizes
View this chart in PDF format

THREAD SIZE	THREAD DEPTH	INSERT DIA.	INSERT LENGTH

ANSI	(in.)	(in.)	(in.)
4-40	0.280	0.500	1.250
6-32	0.345	0.625	1.250
8-32	0.410	0.625	1.250
10-32	0.475	0.625	1.250
1/4-20	0.625	0.625	1.250
5/16-18	0.781	0.625	1.250
3/8-16	0.938	0.625	1.250
1/2-13	1.250	0.750	2.000
5/8-11	1.550	1.000	2.250
3/4-10	1.875	1.250	3.000
1-8	2.500	1.250	3.000

METRIC	(mm)	(in.)	(in.)
M3 x 0.5	7.50	0.281	1.000
M4 x 0.7	10.00	0.500	1.000
M5 x 0.8	12.50	0.500	1.000
M6 x 1	15.00	0.625	1.250
M8 x 1.25	20.00	0.625	1.250
M10 x 1.5	25.00	0.625	2.000
M12 x 1.75	30.00	0.750	2.000
M16 x 2	40.00	1.250	2.250
M20 x 2.5	50.00	1.250	2.500
M24 x 3	60.00	1.250	3.000

TAPERED
1/8 NPT		0.625	0.750
1/4 NPT		0.750	1.250
3/8 NPT		1.000	2.000
1/2 NPT		1.250	2.000

SOLID BLANK
SOLID BLANK		0.500	1.250
SOLID BLANK		0.625	1.250
SOLID BLANK		0.750	2.000
SOLID BLANK		1.000	2.000

Holes
Tru-stone is capable of providing holes for location, clearance or weight reduction. Holes range from as small as .188” for air ports to large wire-sawn holes for hubs or clearance. If a hole must be placed near the edge, a good rule of thumb for design is to maintain a wall thickness of at least the diameter of the hole between the hole and the edge. This can vary with the size of the hole and thickness of the granite of course.

Straight Thru-Hole	Counterbored Hole	Double Counterbored Hole

Slots
T-slots are commonly incorporated into granite bases for flexibility in fastener location. T-slots are typically milled into steel bar stock and glued into the granite base. T-slots can also be milled into the granite if required for your application.

Common slot	Embedded steel slot	Replaceable steel slot

Slots milled into granite

LVDT
Adapters for LVDT Transducer assemblies are available in our typical configuration shown here or in a custom configuration to meet your application requirements.

Example of an LVDT assembly