Specialist services such as deep hole boring, deep hole drilling and honing are a black art to some and still slightly grey for others.
Modern apprenticeships do not cover such skill sets and even the traditional apprenticeships from decades ago only ever covered honing or grinding in a minimal format.
This can often make it difficult for buyers looking to procure these services as there can be a whole host of complications and confusion over cost versus quality, which can arise simply through specifying the level of machining, the technical specification and the overall impact on the finished component.
What Do We Mean By This?
Firstly, let’s take the issue of tolerances achievable by these services. When quoting deep hole drilling or gundrilling, which is most commonly used to drill bores from 2mm – 20mm diameter, the standard industry tolerance up to 10mm diameter would be ±0,05mm. However, anything in excess of 10mm diameter, a safe tolerance to quote would be ±0,1mm.
For deep hole boring which would be utilised on bores from 20mm – 200mm+ diameter, a standard, industry tolerance quoted would be ±0,25mm. Therefore, any tolerances below these parameters result in a requirement for honing.
However, adding honing to the cost of the sub-contract machining can often result in our quotation not being as cost-effective as the prices offered by our competitors.
The choice here is, do we simply quote our standard tolerance and guarantee to win the work with the lowest price? Or, do we quote on a basis which will ensure the quality our customer requires, as well as preventing them from having a surprise additional cost or delay to the promised lead time when half way through the order the tolerance isn’t achieved? The same applies to surface finishes.
At Hone-All Precision, we always take a cautious approach to our work as quality must be paramount; furthermore, the costs and lead time must be known in full at the start of the project to ensure accurate and competitive project costs for our customers to submit to their clients.
