Make the part from tool steel to have a close sliding fit in the slot and to hold a 3/4 boring bar, thread/tap for a screw to hold the bar and slit and thread another hole for a screw to expand it against the T-slot, or whatever retaining means you want. This is a very cool tool, not quite as precise, if you are aiming for tenths as a Wohlhaupter, but from the you-tube videos, it looks like you can get under. There are some images of the cartridge on in the videos below, and you can find images via a web search. Some reviews complain about rigidity compared to a "regular" boring head.I do not have a Bridgeport so I haven't repeated the tests shown in the video or attempted to duplicate the complaints (my Mill is a 40 taper machine of much larger size, I have a Wohlhaupter head if I need these features). Both videos are generally positive, the main drawback they mention is that the unit uses up some of the height above table on the mill. The unit is made by Machine & Eng Co, South El Monte, CA, serial number is 653 B. Check out my other items. The item "BoreMate boring & facing head for Bridgeport Mill, R8 shank, model T.
BPT" is in sale since Sunday, June 13, 2021. This item is in the category "Business & Industrial\CNC, Metalworking & Manufacturing\Workholding & Toolholding\Toolholding\Adapters & Holders\Boring Head & Adapters". The seller is "william_b_noble" and is located in Santa Monica, California. This item can be shipped to United States, Canada, United Kingdom, Denmark, Romania, Slovakia, Bulgaria, Czech republic, Finland, Hungary, Latvia, Lithuania, Malta, Estonia, Australia, Greece, Portugal, Cyprus, Slovenia, Japan, China, Sweden, South Korea, Indonesia, Taiwan, South africa, Thailand, Belgium, France, Hong Kong, Ireland, Netherlands, Poland, Spain, Italy, Germany, Austria, Bahamas, Israel, Mexico, New Zealand, Singapore, Switzerland, Norway, Saudi arabia, Ukraine, United arab emirates, Qatar, Kuwait, Bahrain, Croatia, Malaysia, Chile, Colombia, Costa rica, Panama, Trinidad and tobago, Guatemala, Honduras, Jamaica, Barbados, Bangladesh, Bermuda, Brunei darussalam, Bolivia, Egypt, French guiana, Guernsey, Gibraltar, Guadeloupe, Iceland, Jersey, Jordan, Cambodia, Cayman islands, Liechtenstein, Sri lanka, Luxembourg, Monaco, Macao, Martinique, Maldives, Nicaragua, Oman, Pakistan, Paraguay, Reunion, Uruguay.