Tools to align frame using HT as reference

[BigPoser]

I've been searching around and don't really know where to go to find what I'm looking for. I'm hoping to find some parts that I can use for my alignment table that would enable me to use the HT as my alignment reference instead of the BB post. I would still use the BB post to ensure the ST is right, but I'd like to use the HT every time after that. Hopefully that makes sense.

Anyone done this have some tips on where to go or what to use?

Thanks in advance.

Brandon

[edoz]

I can't think of a ready made solution off the top off my head, but Alex Meade makes surface plate fixturing and if he doens't already make what you want I'm sure he would. I think
his website is alexmeade dot com

[Andrew R Stewart]

Eric has it right IMO. My HT alignment fixture was made by Alex Meade. Here's a shot of one end of the HT fixture. Note the brass shim placed between the base and the tower. This is to tune the two towers' height, or to better make parallel the through rod WRT the table surface. Not shown is a mechanist's screw jack that supports the middle point of the seat tube. It is set to make the ST's center the same height off the table surface. Now the 3 points are established, the two ends of the HT and the center of the ST. A dial or indicator at either end of the ST will display any twist.

I first learned this as being the Bontrager method. Andy

IMG_1488.jpg

[BigPoser]

Eric has it right IMO. My HT alignment fixture was made by Alex Meade. Here's a shot of one end of the HT fixture. Note the brass shim placed between the base and the tower. This is to tune the two towers' height, or to better make parallel the through rod WRT the table surface. Not shown is a mechanist's screw jack that supports the middle point of the seat tube. It is set to make the ST's center the same height off the table surface. Now the 3 points are established, the two ends of the HT and the center of the ST. A dial or indicator at either end of the ST will display any twist.

I first learned this as being the Bontrager method. Andy

IMG_1488.jpg

That looks about right. Do you have everything secured to you table?

I used this: BikeMachinery while at Dave Bohm's school over the last couple of weeks and really liked it. He has the jig mounted horizontally and it's killer. Trying to get the next best set up if possible.

I'll check out what Alex has to offer.

[shand]

Look for a pair of bench centres.

panel_4_1.jpg

I'm pretty sure I wrote up a pice on the Salon on how I used to handle alignment based on the HT.

Edit better pic here : https://www.velocipedesalon.com/foru...tml#post499528

[Andrew R Stewart]

Brandon- My HT set up is mounted on a piece of mic 6 Al plate (I think that's what it's called, bought a bunch 35+ years ago. It's flat and thickness to a tiny spec per foot). Since I don't do any actual aligning when the frame is mounted on it I don't feel the need to secure the set up to my surface plate. I have a common (self designed and locally made) BB post for that stuff. "Bench center" is the term I was looking for but couldn't remember when I typed my first reply. But looking at their cost... This is why I sought out Alex for his towers and cones.

Steven- I think I remember the thread you linked to. It will be fun to reread it later, thanks. Andy

[Ben Hudson]

Sigma made bench centres which are reasonably easy to get hold of in the UK; probably less so in the US although there is one in Canada on eBay right now.

[devlin]

Steven Shand's method is awesome and it's something I'm working towards. I am currently using adjustable rests for the seat tube and head tube and then the BB just rest on the post. It's a crude version of what Dazza does at Llewellyn. He fixes the seat tube as opposed to Stevens fixing the head tube. Neither is better than the other when your process works to that.

[EricKeller]

I think that precision bench centers for shaft metrology are probably easily available on the surplus market for not much money. Some of them are pretty tall though. I have one, still haven't mounted it at the end of my granite slab. So far, all of this has been free, but I was in the right place at the right time.

[jclay]

I use the rod and cones from my frame fixture, some vee blocks and a couple of beam clamps to secure the assembly to my table so I can lean on the frame to correct the alignment as it's being tacked. Economical and suitable for non-production environments.

[jclay]

I use the rod and cones from my frame fixture, some vee blocks and a couple of beam clamps to secure the assembly to my table so I can lean on the frame to correct the alignment as it's being tacked. Economical and suitable for non-production environments.

I use the rod and cones from this: Flickr

and the machined Vee blocks + Jorgenson clamps (left) and the home-made, adjustable vee block under the ST, here: Flickr

Perhaps you already have the components, or some of them. This approach isn't as slick or quick as a store-bought bench center assy but it's economical, not really that fiddly, functionally equivalent and more than adequate for the hobbiest. Actually, unless in an honest to goodness production environment, it's adequate for a pro.

Everybody gets to pick their own toys and proclivities, but in my opinion a dial indicator is over the top for aligning a bicycle frame. The pointer thingy, here (lower left): Flickr
and the adjustable Vee-alignment/Drop-out centering tool at the top, center of the same photo, are more than adequate for the task. The set-up in the last photo was just to satisfy my curiosity.

[BigPoser]

Thank you for the posts and suggestions. It seems there are a few ways I can get this done. I've been searching for various items on the interweb and just need to figure out which way to go.