All of these questions and more can be answered in our Techni-Grip catalog, which you can download below.
~ How big/deep does the dovetail need to be?
.125” is the recommended depth of your 60 degree dovetail and you should attempt to spread the dovetail cuts as wide as your work-piece will allow. The wider the dovetail platform the more stabilized your stock will be. Please see our General Prep video for more details.
~ How close (tolerance wise) do I need to hold the .500” diameters for the locating pins?
The actual truth is “it depends”. The locating pins are manufactured to a diametrical dimension of .4980/.4987”. The tolerances of your applications will dictate how tightly you need to hold your .500” diameter pin locations.
If you are working with +/- .030 tolerances you will not need to be as tightly controlled as an application with .0025” true position tolerances would be. Please refer to our General Prep video for more details.
~ How tightly do I need to hold the parallelism of the dovetail cuts in my work-piece?
As the clamp assemblies are floating within a given range of motion (fixture width), the dovetails need not be held to tight parallelism and can be offset as long as the .500” diameters are in-line. Please see our General Prep video for more details.
~ What is the distance between locating pins and clamps?
All our fixtures models utilize the same part/work-piece locating features and configuration/dimensions. The locating pins and clamp bores are all on 1.375 center to center locations.
~ How much torque should I use on the dovetail clamps?
This is probably the best question that can be asked and a critical one! Do not exceed 25 ft lbs of torque on the clamps at any time. 25 ft lbs is the maximum torque necessary for hard materials such as heat-treated steel, titanium, Inconel, etc.. It is rarely, if ever, necessary to use more than 15 ft lbs for even the largest aluminum work-piece. Small work-pieces can be run with inch lbs of torque.
Over torqueing the dovetail clamps is self-defeating with our fixture design and will cause pre-loaded stress induced into the dovetail to create a concave condition in the base of the work-piece. This pre-loaded, concaved material will proceed to vibrate under the natural harmonics of any cut and act as a tuning fork. This will result in the dovetail clamps loosening while under the cut.
We have never had dovetail clamps loosen if the 25 ft lb maximum guideline is followed.
~ What are the fixtures made of?
The fixture bodies are 6061-T651 aluminum with a hard anodize finish of .002” (providing a surface thickness of .001”). The dovetail clamp bodies are 15-5 ferrite-free steel heat treated to 180/200 ksi. The locating pins are also 15-5 stainless steel but not heat treated.
~ How large can my work-piece be? Can I hang over the edges of the fixture?
Your work-piece limitations are not dictated by the fixture size itself. As a very general guideline you can easily use a 14lb per linear inch of fixture as a suggested maximum weight value. This would yield a 336lb weight workpiece weight for one of our 24” fixtures.
With hi-speed shallower cutter passes you will also be able hang a good amount of material over the sides and ends of your Techni-Grip. Customers have had very good success with as much as 8.000” of unsupported of raw material hanging off the end or side of our fixtures.
~ How do I get rid of the dovetail when my part is finished?
In a 3-axis application you might be able to use a slit saw tool to cut the dovetail away or it may be necessary to flip the part over and hold it in soft jaws to cut away the dovetail.
With 4th and 5th axis capability you may be able to program your part complete in a single milling operation and simply break the completed part off of the dovetail stock. Please see our Single Operation video for more details.
~ What is the Techni-Grip return policy/Terms & Conditions?
If you are not 100% satisfied with your Techni-grip purchase, simply contact us within 30 days and we’ll be happy to arrange for a full refund. Any product you return must be in the same condition as it was when it was received. You can click here, to read our terms and conditions.