I have the chassis with 3 holes on each side that hold the cage on. My ST-70 is missing the screws.
Can someone tell me the size? are they 4-40 1/4"?
Can someone tell me the size? are they 4-40 1/4"?
4 posters
ST-70 chassis to cage screw sizes?
Kray- Posts : 36
Join date : 2019-05-06
Age : 50
Location : Denver
Bob Latino- Admin
- Posts : 3276
Join date : 2008-11-26
Location : Massachusetts
Kray wrote:I have the chassis with 3 holes on each side that hold the cage on. My ST-70 is missing the screws.
Can someone tell me the size? are they 4-40 1/4"?
The holes in the chassis that hold the ST-70 cage on are not for 4-40 screws .. Those holes are for #6 screws. I believe most (if not all) of the original Dynaco ST-70's used self-tapping #6 screws. Try first a 6-32 self tapping screw in your chassis. The modern VTA amp kits use stainless steel 6-32 screws in a tapped hole in the chassis.
Bob
Peter W.- Posts : 1351
Join date : 2016-08-07
Location : Melrose Park, PA
The OEM Dynaco screws were slotted-head 6-32 wood screws. They were 'self-tapping" only after a manner of speaking given that the chassis was a very mild plated steel.
The modern equivalent in Philips-head, stainless (an excellent idea and choice!) is:
https://www.mcmaster.com/90087a143
I understand that Bob's chassis uses a heavier steel than OEM - you might consider going to 1/4" for that reason. But OEM was 3/16. And self-tapping screws would also help with a harder steel. Cheap enough to replace them all in a vintage piece if needed.
The modern equivalent in Philips-head, stainless (an excellent idea and choice!) is:
https://www.mcmaster.com/90087a143
I understand that Bob's chassis uses a heavier steel than OEM - you might consider going to 1/4" for that reason. But OEM was 3/16. And self-tapping screws would also help with a harder steel. Cheap enough to replace them all in a vintage piece if needed.
Kray- Posts : 36
Join date : 2019-05-06
Age : 50
Location : Denver
Bob Latino wrote:Kray wrote:I have the chassis with 3 holes on each side that hold the cage on. My ST-70 is missing the screws.
Can someone tell me the size? are they 4-40 1/4"?
The holes in the chassis that hold the ST-70 cage on are not for 4-40 screws .. Those holes are for #6 screws. I believe most (if not all) of the original Dynaco ST-70's used self-tapping #6 screws. Try first a 6-32 self tapping screw in your chassis. The modern VTA amp kits use stainless steel 6-32 screws in a tapped hole in the chassis.
Bob
Thanks Bob and PeterW
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Last edited by PeterCapo on Mon Nov 30, 2020 8:36 pm; edited 1 time in total
Peter W.- Posts : 1351
Join date : 2016-08-07
Location : Melrose Park, PA
PeterCapo wrote:Original Dynaco parts list specified #6 sheet metal screws.
Here are some that retain the original look, as well: https://www.boltdepot.com/Sheet_metal_screws_Slotted_pan_head_Stainless_steel_18-8_6.aspx
Should have written "Pan Head" wood screws.
18-8 would be the material, 18-8 Stainless.
1/4" is too long for OEM - but not for later (Blackwood) Dynaco products.
The slotted head, however, is a nice touch.
Dale Stevens- Posts : 206
Join date : 2014-07-06
Age : 75
Location : Loris, SC
I've found a good source for stainless hardware is FASTENAL OEM fasteners, which can be found locally so as not to have to order . Just a thought. Dale