I guess I will have to get a new rack manufactured as it seems these parts are not available. I think I will have a machine shop make it from aluminum unless someone has a better idea.
Bits off both ends are missing so I don't know exactly how long it is suppose to be. Anyone know?
M VII plastic rack details
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Do you have a picture of what is left of the part?drdale wrote:I guess I will have to get a new rack manufactured as it seems these parts are not available. I think I will have a machine shop make it from aluminum unless someone has a better idea.
Bits off both ends are missing so I don't know exactly how long it is suppose to be. Anyone know?
If the solution is to get a new one locally manufactured, check with a fabrication shop before going to a machine shop. Much cheaper rates (still not cheap though), and a lot of overlap in what they do except when extreme precision is needed.
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BuckeyeDennis
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Did you see this thread? https://forum.shopsmith.com/viewtopic.php?t=12768
Redleg, a new member, devised a clever way to make his own Mark VII replacement rack.
Redleg, a new member, devised a clever way to make his own Mark VII replacement rack.
There are sections missing off each end. I have 3 small chunks (like shown) I found but there is obviously more missing than that. Kind of floppy at the ends and hard to engage the gears without breaking off more. Either I have to replace it or ge rid of all of it and not have the fine adjustment anymore.
Thanks BuckeyeDennis for the pitch.
drdale Total length is 30 1/4 ". The original gear rack was made in two pieces each piece was 15 1/8 inches long. The holes in each rack section are 3/4" from each end and then one in the center of each section. You should have six holes in your front way tube unless someone has modified with extra holes to hold broken pieces. While this was my first Mark VII and I bought another for parts yesterday I have refurbished a dozen or so Mark V, Total Shop and a master something since I retired two years ago. I will try to answer any questions you might have but a technical writer I am not. Good luck!
drdale Total length is 30 1/4 ". The original gear rack was made in two pieces each piece was 15 1/8 inches long. The holes in each rack section are 3/4" from each end and then one in the center of each section. You should have six holes in your front way tube unless someone has modified with extra holes to hold broken pieces. While this was my first Mark VII and I bought another for parts yesterday I have refurbished a dozen or so Mark V, Total Shop and a master something since I retired two years ago. I will try to answer any questions you might have but a technical writer I am not. Good luck!
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JPG
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Mark VII gear rack dimensions
From what I have been able to determine, the gear rack extends from 2 1/2" from the end 'left' end of the way tube and extends out to 32 3/4" from the left end.
The gear pressure angle is 14 1/2 degree and the pitch is '12' which provides 3.82 teeth/inch.
The gear rack is in two pieces 15 1/8" each or 58 teeth.
The rack width is 9/16".
The rack overall 'thickness' at the edges is 5/16".
The 'tooth depth' is 3/16".
The way tube back side is concave with a 7/8" radius to match the tube 1 3/4" od.
The rivets securing the gear rack to the tube are spaced as follows starting at the left end of the rack. All the rivets are centered between adjacent gear teeth.
Between tooth 3 and 4, 29 and 30, 55 and 56, 61 and 62, 87 and 88, and 113 and 114.
The two gear racks are identical and symmetrical.
If you are serious about getting a machine shop to do this, start off with off the shelf gear racks and cut them to width and to the concave back. You do not want to pay for machining all those teeth. A 3/4" wide rack MAY work, but I have not examined that closely.
I am seeing off the shelf steel gear racks in 4 ' lengths for approx $75. IIRC, nylon racks were more $$$$$.
This ain't cheap!
The gear pressure angle is 14 1/2 degree and the pitch is '12' which provides 3.82 teeth/inch.
The gear rack is in two pieces 15 1/8" each or 58 teeth.
The rack width is 9/16".
The rack overall 'thickness' at the edges is 5/16".
The 'tooth depth' is 3/16".
The way tube back side is concave with a 7/8" radius to match the tube 1 3/4" od.
The rivets securing the gear rack to the tube are spaced as follows starting at the left end of the rack. All the rivets are centered between adjacent gear teeth.
Between tooth 3 and 4, 29 and 30, 55 and 56, 61 and 62, 87 and 88, and 113 and 114.
The two gear racks are identical and symmetrical.
If you are serious about getting a machine shop to do this, start off with off the shelf gear racks and cut them to width and to the concave back. You do not want to pay for machining all those teeth. A 3/4" wide rack MAY work, but I have not examined that closely.
I am seeing off the shelf steel gear racks in 4 ' lengths for approx $75. IIRC, nylon racks were more $$$$$.
This ain't cheap!
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Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
╟JPG ╢
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Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
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JPG
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- Location: Lexington, Ky (TAMECAT territory)
drdale wrote:Did they make the rack in 2 pieces so you can install it one piece at at time at one end and then move the headstock to the other end and install the second piece?
I would guess it has something to do with maximum injection molding length and that they were installed simultaneously sans any thing else.
I do not think 'in the field' replacement was a consideration.
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Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
╟JPG ╢
╚═══╝
Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
Thanks so much for the detailed information on the gear rack. I did some checking on replacing it with off-the-rack possibilities and so did a machine shop guy I know.
Anyway, he offered to make me one from aluminum and I told him to go ahead. He projects about $150 - $175. This seem fair to me. I will let you know how it works out.
Anyway, he offered to make me one from aluminum and I told him to go ahead. He projects about $150 - $175. This seem fair to me. I will let you know how it works out.