Bessey J Series Step-Over Clamps
Uncommon solution for common obstructions
Text, photos and video by Tom Hintz
Posted – 11-24-2010
If everything we need to clamp up was flat our clamping life would be way easier. However, our in-shop reality is far more complicated so the Bessey J Series Step-Over Clamps can be considered to be something of a mechanical savior. Because having to reach over obstructions to apply clamping pressure is not uncommon we need a clamp style that can both clear obstructions and still apply dependable pressure. The Bessey J Series Step-Over Clamps are up to that challenge – and then some.
The Bessey J Series Step-Over Clamps are built to be very tough using high quality Bessey steels that are fabricated and processed with proprietary heat-treating sequences. The clamping bar has the familiar hourglass shape that dramatically increases rigidity to help apply the tremendous pressures predictably and without distortion or fear of failure.
The Bessey J Series Step-Over Clamps rail is formed to provide the step-over reach yet retain the critical strength and rigidity. The Bessey J Series Step-Over Clamps is available in three sizes and four models. The J18-8 has a step-over capacity of 2-3/4”, a 4-3/4”-throat depth, 10” clamping capacity and can generate 880-lbs of clamping pressure. The 2400J-12 has 4” of step-over capacity, 5-1/2” throat depth, 12”-clamping capacity and generates 2660-lbs of clamping force. Finally the 4800j-20 has a 6”-step-over capacity, 7” throat depth, 20”-clamping capacity and generates a tough 4880-lebs of clamping force!
Tough Sliding Arm
Adjusting the Bessey J Series Step-Over Clamps for the size of the work is quick thanks to the sliding arm. Despite the bar not having serrated edges the boss on the sliding arm locks to the bar instantly when pressure is applied and resists slipping even under the huge clamping pressures these clamps generate. Just slide the arm into position and tighten the spindle, often less than a full revolution to lock the Bessey J Series Step-Over Clamps in place with plenty of pressure for the job.
The sliding arm is drop forged and specially heat-treated to insure proper function over a long service life. The shape of the sliding bar was designed to help it resist distortions when pressure is applied. The bosses at the bar and spindle are both sized to resist the forces and to make the Bessey J Series Step-Over Clamps easy to use.
The Bessey J Series Step-Over Clamp spindles are machined from special high-carbon steel and formed with the Acme thread design that applies high level of pressure without high levels of user input. While this thread design inherently resists contamination well, Bessey subjects them to tempering and quenching routines that substantially increases their overall strength, durability and resistance to welding spatter.
The J18-8 has a sliding handle (Tommy Bars) permanently installed in the end of the spindle. The 2400J models have a special ergonomic handle that makes them even more comfortable and user-friendly. The 4800J series Bessey J Series Step-Over Clamps have a large sliding bar handle but also incorporates a hex head that can be turned with a wrench to gain even more leverage and comfort. In all cases, the handles are designed to let the user generate plenty of clamping force with minimal effort. Being able to slide the handles from one side of the spindle to the other makes using the Bessey J Series Step-Over Clamps in confined areas easier.
All of the Bessey J Series Step-Over Clamps have a round, steel pad welded to the bar. This fixed pad is carefully aligned to be 90-degrees to the bar to help apply pressure evenly with less slippage.
The spindle side of the J18 clamps have a round swivel-mounted pad that helps get a firm grip on surfaces that are not exactly parallel with the opposing side. The 2400J and 4800J clamps come with the exclusive Bessey MorPad that features a specially designed and manufactured ball and socket that is designed to withstand the tremendous clamping pressures without failing or losing pressure over time.
In the Shop
Using the Bessey J Series Step-Over Clamps is easy because of the quality of their design and manufacturing. The fit between the sliding arm boss and the bar itself is consistently close. That insures that the arm locks in place as soon as pressure is applied. Despite cranking down on the spindle handles far more than was needed I have yet been able to make the sliding arm slip even a little at all once a little pressure is applied. That fit and immediate locking when you turn the spindle makes the Bessey J Series Step-Over Clamps very easy to put in place even in odd positions.
It is also obvious that Bessey was not concerned with weight when designing the Bessey J Series Step-Over Clamps. Instead they used all of the high-quality steel that was necessary to handle the substantial clamping forces possible. Here again, despite me cranking in way more pressure than was needed, I could find no distortions or note any slipping once pressure was being applied.
As far as maintenance is concerned I expect that we just need to brush them off now and then and remember not to leave them on train tracks. I think that they can handle everything else and maybe a train or two as well.
With a street price of $72.95 (11-23-2010) for the J18-8 model, $137.50 for the 2400J-12 and $199.00 for the 4800J-20 may not be cheap to start with but when you need this kind of clamping capabilities the Bessey J Series Step-Over Clamps can be a real lifesaver. Factor in their extreme durability, virtually perpetual life expectancy and the Bessey J Series Step-Over Clamps become a good investment for your productivity as well as a less troubled state of mind in the shop!