Got one of the 763 Diamond Glass blanks from Ron at Hook and Hackle, and it is a beauty. The butt end measures OD .445, and I’m having a problem finding a reel seat to fit it. (Problem compounded by wanting a sliding ring, down-locking reel seat!) Can find some really pretty ones through REC, but even custom boring only goes to .438. Is it much of a trick to use a round file and enlarge the bore? Is there a company I have yet to hear about that produces a sliding ring, down-locking reel seat with a larger standard bore? 
Betty for a difference of only .007 I’d ream it to a perfect fit.
A couple of passes with a rat tail file will probably be plenty. You may want to get a large enough file to really minimize the work and keep it as round as possible.
Erik
Betty -
Struble does a lot of reel seats with a .460 ID. Don’t know if they would have a sliding ring down locking reel seat in that dimension.
I’m with Ray on reaming the one you want for the perfect mechanical fit.
John
Slide Riing? Down lock?..
Get the tail tail file out deary…Ed
Might also look here…http://www.strublemfg.com/product/?tag=seat
Larger I.D.'s are available up to .460
Hello Betty, careful if you go Struble D2 and start rattailing…it’s shipped .375 for a reason and though I did some work on one and made it a bit larger in the I.D., no way would I trust one hogged out to .445 (plus what you’ll need for glue clearance)…the mortise is the reason it won’t go much larger in the I.D. and there just isn’t enough wood left under the mortise so support the clamping forces required to keep your fly reel in place.
What would happen at .445 I.D. would be smiles and ‘ohhh pretty’ from you upon accomplishing the modification but an ‘ohhhhh noooooo’ when you tried keep a reel on since the mortise would likely split or collapse.
That being said and guessing how badly you want a dl slide band, you might have one made
which wouldn’t be a big deal and I bet you…I just bet you…someone right here in FAOL is going to offer such. Hopefully short of that, you’ll find a dl slideband seat with the I.D. you need.
Cheers,
MontanaMoose
Betty
I made a sliding band reel seat for my tricked out Tadpole and the butt diameter is .485. It was a tight fit, but it worked. Just get a rat tail file, go SLOW and you will be OK.
Brad
Betty,
That Dglass has a pretty steep taper, so you will only need to take a little material out of one end of an REC insert. REC makes most of their inserts with stabilized wood, so splitting is less likely.
Another option is a cork insert instead of wood. That lightens the rod even more. But cork inserts eventually get dented up if the sliding ring doesn’t have an internal taper. Rings with an internal taper hold great on cork. Cork can be worked fairly thin without splitting.
The hardest option, but most versatile, is to cut off the last 4 inches of the rod butt and insert a plug of dowel or graphite rod into the remaining blank. The OD of the plug is sized to fit into the reelseat. This allows using any reelseat you desire. Tom Morgan’s upcoming line of glass blanks will come with a plug dowel and trimming instructions for just that purpose (see the 9th paragraph on the page).
Tom
You guys are the best!! Thank you! Will post up on this rod as it progresses!
Sent you a pm.
PM found and responded to!! Thank you!
Hi Betty,
I ran into the same problem with a 7 1/2’ Lami blank. I got the CRA reel seat from REC with the maximum custom bore. It wound up fitting perfectly, but I was ready to file out the butt end of the seat to make the steep taper fit. I think jgestar has it dialed in just right. It will be tight, but it should fit very well with plenty of room for glue.
I’m just tickled that I have the chance to forward some valuable information to a PRO rod builder. 
Thanks for the good laugh, Joe!! I did order the CRN for the 763 and the CRNS for the 502, with matching wood inserts. Will head to the hardware store today for a fine rat tail file, none of the ones I have now would be small enough for this project! Depending on the colors of the wood (gotta see it when it gets here … each is so different) the thread wraps will be in the claret/cranberry line. Excited to see how they progress.
Would like to try the spigot type extension, with the cutting off of part of the blank, but that’s got to wait till I find a REALLY inexpensive blank to try it on!!
I never could file out a round hole, always lopsided. If you have an old blank of a suitable diameter, apply some adhesive backed sand paper and ream away. Clean out the seat well, the loose grit left behind can come back to haunt you.
I’ve been at the Midwest Fly Fishing Expo so I’ve missed all the hoopla about the insert bore.
You received good advice and I’m impressed! I’d probably hit it with the rat tail file too.
Thinking about this, I just wanted to warn folks to be careful if they attempt to hand drill these bores to a large diameter. These hard woods break easily. If you need to drill it, results will be better with a drill press, rather than a hand drill.
Ron
Betty, before Ron started handling the DB blanks, I got one from Cortland, and was flabbergasted at how big the butt was - like mine!
Anyway, I called Cortland and they supplied me with a nice seat that fit fine.
I didn’t know they had that service!! And I think I covered their web site pretty closely! Wow! Did order a REC, and am curious to see what it’s like … should be here by weeks end.